ed: fix "\n" removal in command line; make "w" set "dirty = 0"
[oweals/busybox.git] / editors / ed.c
index 1706e427174b089d98fe6c71c91636a1169f1645..7f21ded927482e9e20d0c809e04e2b5941ef5a60 100644 (file)
@@ -6,14 +6,23 @@
  *
  * The "ed" built-in command (much simplified)
  */
+//config:config ED
+//config:      bool "ed (25 kb)"
+//config:      default y
+//config:      help
+//config:      The original 1970's Unix text editor, from the days of teletypes.
+//config:      Small, simple, evil. Part of SUSv3. If you're not already using
+//config:      this, you don't need it.
 
-#include "busybox.h"
+//kbuild:lib-$(CONFIG_ED) += ed.o
 
-enum {
-       USERSIZE = sizeof(bb_common_bufsiz1) > 1024 ? 1024
-                : sizeof(bb_common_bufsiz1) - 1, /* max line length typed in by user */
-       INITBUF_SIZE = 1024, /* initial buffer size */
-};
+//applet:IF_ED(APPLET(ed, BB_DIR_BIN, BB_SUID_DROP))
+
+//usage:#define ed_trivial_usage "[FILE]"
+//usage:#define ed_full_usage ""
+
+#include "libbb.h"
+#include "common_bufsiz.h"
 
 typedef struct LINE {
        struct LINE *next;
@@ -24,355 +33,589 @@ typedef struct LINE {
 
 #define searchString bb_common_bufsiz1
 
-static LINE lines, *curLine;
-static int curNum, lastNum, marks[26], dirty;
-static char *bufBase, *bufPtr, *fileName;
-static int bufUsed, bufSize;
-
-static void doCommands(void);
-static void subCommand(const char *cmd, int num1, int num2);
-static int getNum(const char **retcp, int *retHaveNum, int *retNum);
-static int setCurNum(int num);
-static int initEdit(void);
-static void termEdit(void);
-static void addLines(int num);
-static int insertLine(int num, const char *data, int len);
-static int deleteLines(int num1, int num2);
-static int printLines(int num1, int num2, int expandFlag);
-static int writeLines(const char *file, int num1, int num2);
-static int readLines(const char *file, int num);
-static int searchLines(const char *str, int num1, int num2);
-static LINE *findLine(int num);
-
-static int findString(const LINE *lp, const char * str, int len, int offset);
-
-int ed_main(int argc, char **argv);
-int ed_main(int argc, char **argv)
-{
-       if (!initEdit())
-               return EXIT_FAILURE;
-
-       if (argc > 1) {
-               fileName = strdup(argv[1]);
-
-               if (fileName == NULL) {
-                       bb_error_msg("no memory");
-                       termEdit();
-                       return EXIT_SUCCESS;
-               }
-
-               if (!readLines(fileName, 1)) {
-                       termEdit();
-                       return EXIT_SUCCESS;
-               }
-
-               if (lastNum)
-                       setCurNum(1);
+enum {
+       USERSIZE = COMMON_BUFSIZE > 1024 ? 1024
+                : COMMON_BUFSIZE - 1, /* max line length typed in by user */
+       INITBUF_SIZE = 1024, /* initial buffer size */
+};
 
-               dirty = FALSE;
+struct globals {
+       int curNum;
+       int lastNum;
+       int bufUsed;
+       int bufSize;
+       LINE *curLine;
+       char *bufBase;
+       char *bufPtr;
+       char *fileName;
+       LINE lines;
+       smallint dirty;
+       int marks[26];
+};
+#define G (*ptr_to_globals)
+#define curLine            (G.curLine           )
+#define bufBase            (G.bufBase           )
+#define bufPtr             (G.bufPtr            )
+#define fileName           (G.fileName          )
+#define curNum             (G.curNum            )
+#define lastNum            (G.lastNum           )
+#define bufUsed            (G.bufUsed           )
+#define bufSize            (G.bufSize           )
+#define dirty              (G.dirty             )
+#define lines              (G.lines             )
+#define marks              (G.marks             )
+#define INIT_G() do { \
+       setup_common_bufsiz(); \
+       SET_PTR_TO_GLOBALS(xzalloc(sizeof(G))); \
+} while (0)
+
+static int bad_nums(int num1, int num2, const char *for_what)
+{
+       if ((num1 < 1) || (num2 > lastNum) || (num1 > num2)) {
+               bb_error_msg("bad line range for %s", for_what);
+               return 1;
        }
-
-       doCommands();
-
-       termEdit();
-       return EXIT_SUCCESS;
+       return 0;
 }
 
 /*
- * Read commands until we are told to stop.
+ * Return a pointer to the specified line number.
  */
-static void doCommands(void)
+static LINE *findLine(int num)
 {
-       const char *cp;
-       char *endbuf, *newname, buf[USERSIZE];
-       int len, num1, num2, have1, have2;
-
-       while (TRUE) {
-               printf(": ");
-               fflush(stdout);
+       LINE *lp;
+       int lnum;
 
-               if (fgets(buf, sizeof(buf), stdin) == NULL)
-                       return;
+       if ((num < 1) || (num > lastNum)) {
+               bb_error_msg("line number %d does not exist", num);
+               return NULL;
+       }
 
-               len = strlen(buf);
+       if (curNum <= 0) {
+               curNum = 1;
+               curLine = lines.next;
+       }
 
-               if (len == 0)
-                       return;
+       if (num == curNum)
+               return curLine;
 
-               endbuf = &buf[len - 1];
+       lp = curLine;
+       lnum = curNum;
+       if (num < (curNum / 2)) {
+               lp = lines.next;
+               lnum = 1;
+       } else if (num > ((curNum + lastNum) / 2)) {
+               lp = lines.prev;
+               lnum = lastNum;
+       }
 
-               if (*endbuf != '\n') {
-                       bb_error_msg("command line too long");
+       while (lnum < num) {
+               lp = lp->next;
+               lnum++;
+       }
 
-                       do {
-                               len = fgetc(stdin);
-                       } while ((len != EOF) && (len != '\n'));
+       while (lnum > num) {
+               lp = lp->prev;
+               lnum--;
+       }
+       return lp;
+}
 
-                       continue;
-               }
+/*
+ * Search a line for the specified string starting at the specified
+ * offset in the line.  Returns the offset of the found string, or -1.
+ */
+static int findString(const LINE *lp, const char *str, int len, int offset)
+{
+       int left;
+       const char *cp, *ncp;
 
-               while ((endbuf > buf) && isblank(endbuf[-1]))
-                       endbuf--;
+       cp = &lp->data[offset];
+       left = lp->len - offset - len;
 
-               *endbuf = '\0';
+       while (left >= 0) {
+               ncp = memchr(cp, str[0], left + 1);
+               if (ncp == NULL)
+                       return -1;
+               left -= (ncp - cp);
+               cp = ncp;
+               if (memcmp(cp, str, len) == 0)
+                       return (cp - lp->data);
+               cp++;
+               left--;
+       }
 
-               cp = buf;
+       return -1;
+}
 
-               while (isblank(*cp))
-                       cp++;
+/*
+ * Search for a line which contains the specified string.
+ * If the string is "", then the previously searched for string
+ * is used.  The currently searched for string is saved for future use.
+ * Returns the line number which matches, or 0 if there was no match
+ * with an error printed.
+ */
+static NOINLINE int searchLines(const char *str, int num1, int num2)
+{
+       const LINE *lp;
+       int len;
 
-               have1 = FALSE;
-               have2 = FALSE;
+       if (bad_nums(num1, num2, "search"))
+               return 0;
 
-               if ((curNum == 0) && (lastNum > 0)) {
-                       curNum = 1;
-                       curLine = lines.next;
+       if (*str == '\0') {
+               if (searchString[0] == '\0') {
+                       bb_error_msg("no previous search string");
+                       return 0;
                }
+               str = searchString;
+       }
 
-               if (!getNum(&cp, &have1, &num1))
-                       continue;
-
-               while (isblank(*cp))
-                       cp++;
-
-               if (*cp == ',') {
-                       cp++;
+       if (str != searchString)
+               strcpy(searchString, str);
 
-                       if (!getNum(&cp, &have2, &num2))
-                               continue;
+       len = strlen(str);
 
-                       if (!have1)
-                               num1 = 1;
+       lp = findLine(num1);
+       if (lp == NULL)
+               return 0;
 
-                       if (!have2)
-                               num2 = lastNum;
+       while (num1 <= num2) {
+               if (findString(lp, str, len, 0) >= 0)
+                       return num1;
+               num1++;
+               lp = lp->next;
+       }
 
-                       have1 = TRUE;
-                       have2 = TRUE;
-               }
+       bb_error_msg("can't find string \"%s\"", str);
+       return 0;
+}
 
-               if (!have1)
-                       num1 = curNum;
+/*
+ * Parse a line number argument if it is present.  This is a sum
+ * or difference of numbers, ".", "$", "'c", or a search string.
+ * Returns pointer which stopped the scan if successful
+ * (whether or not there was a number).
+ * Returns NULL if there was a parsing error, with a message output.
+ * Whether there was a number is returned indirectly, as is the number.
+ */
+static const char* getNum(const char *cp, smallint *retHaveNum, int *retNum)
+{
+       char *endStr, str[USERSIZE];
+       int value, num;
+       smallint haveNum, minus;
 
-               if (!have2)
-                       num2 = num1;
+       value = 0;
+       haveNum = FALSE;
+       minus = 0;
 
-               switch (*cp++) {
-                       case 'a':
-                               addLines(num1 + 1);
-                               break;
+       while (TRUE) {
+               cp = skip_whitespace(cp);
 
-                       case 'c':
-                               deleteLines(num1, num2);
-                               addLines(num1);
+               switch (*cp) {
+                       case '.':
+                               haveNum = TRUE;
+                               num = curNum;
+                               cp++;
                                break;
 
-                       case 'd':
-                               deleteLines(num1, num2);
+                       case '$':
+                               haveNum = TRUE;
+                               num = lastNum;
+                               cp++;
                                break;
 
-                       case 'f':
-                               if (*cp && !isblank(*cp)) {
-                                       bb_error_msg("bad file command");
-                                       break;
-                               }
-
-                               while (isblank(*cp))
-                                       cp++;
-
-                               if (*cp == '\0') {
-                                       if (fileName)
-                                               printf("\"%s\"\n", fileName);
-                                       else
-                                               printf("No file name\n");
-                                       break;
-                               }
-
-                               newname = strdup(cp);
-
-                               if (newname == NULL) {
-                                       bb_error_msg("no memory for file name");
-                                       break;
+                       case '\'':
+                               cp++;
+                               if ((unsigned)(*cp - 'a') >= 26) {
+                                       bb_error_msg("bad mark name");
+                                       return NULL;
                                }
+                               haveNum = TRUE;
+                               num = marks[(unsigned)(*cp - 'a')];
+                               cp++;
+                               break;
 
-                               if (fileName)
-                                       free(fileName);
-
-                               fileName = newname;
+                       case '/':
+                               strcpy(str, ++cp);
+                               endStr = strchr(str, '/');
+                               if (endStr) {
+                                       *endStr++ = '\0';
+                                       cp += (endStr - str);
+                               } else
+                                       cp = "";
+                               num = searchLines(str, curNum, lastNum);
+                               if (num == 0)
+                                       return NULL;
+                               haveNum = TRUE;
                                break;
 
-                       case 'i':
-                               addLines(num1);
+                       default:
+                               if (!isdigit(*cp)) {
+                                       *retHaveNum = haveNum;
+                                       *retNum = value;
+                                       return cp;
+                               }
+                               num = 0;
+                               while (isdigit(*cp))
+                                       num = num * 10 + *cp++ - '0';
+                               haveNum = TRUE;
                                break;
+               }
 
-                       case 'k':
-                               while (isblank(*cp))
-                                       cp++;
+               value += (minus ? -num : num);
 
-                               if ((*cp < 'a') || (*cp > 'a') || cp[1]) {
-                                       bb_error_msg("bad mark name");
-                                       break;
-                               }
+               cp = skip_whitespace(cp);
 
-                               marks[*cp - 'a'] = num2;
+               switch (*cp) {
+                       case '-':
+                               minus = 1;
+                               cp++;
                                break;
 
-                       case 'l':
-                               printLines(num1, num2, TRUE);
+                       case '+':
+                               minus = 0;
+                               cp++;
                                break;
 
-                       case 'p':
-                               printLines(num1, num2, FALSE);
-                               break;
+                       default:
+                               *retHaveNum = haveNum;
+                               *retNum = value;
+                               return cp;
+               }
+       }
+}
 
-                       case 'q':
-                               while (isblank(*cp))
-                                       cp++;
+/*
+ * Set the current line number.
+ * Returns TRUE if successful.
+ */
+static int setCurNum(int num)
+{
+       LINE *lp;
 
-                               if (have1 || *cp) {
-                                       bb_error_msg("bad quit command");
-                                       break;
-                               }
+       lp = findLine(num);
+       if (lp == NULL)
+               return FALSE;
+       curNum = num;
+       curLine = lp;
+       return TRUE;
+}
 
-                               if (!dirty)
-                                       return;
+/*
+ * Insert a new line with the specified text.
+ * The line is inserted so as to become the specified line,
+ * thus pushing any existing and further lines down one.
+ * The inserted line is also set to become the current line.
+ * Returns TRUE if successful.
+ */
+static int insertLine(int num, const char *data, int len)
+{
+       LINE *newLp, *lp;
 
-                               printf("Really quit? ");
-                               fflush(stdout);
+       if ((num < 1) || (num > lastNum + 1)) {
+               bb_error_msg("inserting at bad line number");
+               return FALSE;
+       }
 
-                               buf[0] = '\0';
-                               fgets(buf, sizeof(buf), stdin);
-                               cp = buf;
+       newLp = xmalloc(sizeof(LINE) + len - 1);
 
-                               while (isblank(*cp))
-                                       cp++;
+       memcpy(newLp->data, data, len);
+       newLp->len = len;
 
-                               if ((*cp == 'y') || (*cp == 'Y'))
-                                       return;
+       if (num > lastNum)
+               lp = &lines;
+       else {
+               lp = findLine(num);
+               if (lp == NULL) {
+                       free((char *) newLp);
+                       return FALSE;
+               }
+       }
 
-                               break;
+       newLp->next = lp;
+       newLp->prev = lp->prev;
+       lp->prev->next = newLp;
+       lp->prev = newLp;
 
-                       case 'r':
-                               if (*cp && !isblank(*cp)) {
-                                       bb_error_msg("bad read command");
-                                       break;
-                               }
+       lastNum++;
+       dirty = TRUE;
+       return setCurNum(num);
+}
 
-                               while (isblank(*cp))
-                                       cp++;
+/*
+ * Add lines which are typed in by the user.
+ * The lines are inserted just before the specified line number.
+ * The lines are terminated by a line containing a single dot (ugly!),
+ * or by an end of file.
+ */
+static void addLines(int num)
+{
+       int len;
+       char buf[USERSIZE + 1];
 
-                               if (*cp == '\0') {
-                                       bb_error_msg("no file name");
-                                       break;
-                               }
+       while (1) {
+               /* Returns:
+                * -1 on read errors or EOF, or on bare Ctrl-D.
+                * 0  on ctrl-C,
+                * >0 length of input string, including terminating '\n'
+                */
+               len = read_line_input(NULL, "", buf, sizeof(buf), /*timeout*/ -1);
+               if (len <= 0) {
+                       /* Previously, ctrl-C was exiting to shell.
+                        * Now we exit to ed prompt. Is in important? */
+                       return;
+               }
+               if (buf[0] == '.' && buf[1] == '\n' && buf[2] == '\0')
+                       return;
+               if (!insertLine(num++, buf, len))
+                       return;
+       }
+}
 
-                               if (!have1)
-                                       num1 = lastNum;
+/*
+ * Read lines from a file at the specified line number.
+ * Returns TRUE if the file was successfully read.
+ */
+static int readLines(const char *file, int num)
+{
+       int fd, cc;
+       int len, lineCount, charCount;
+       char *cp;
 
-                               if (readLines(cp, num1 + 1))
-                                       break;
+       if ((num < 1) || (num > lastNum + 1)) {
+               bb_error_msg("bad line for read");
+               return FALSE;
+       }
 
-                               if (fileName == NULL)
-                                       fileName = strdup(cp);
+       fd = open(file, 0);
+       if (fd < 0) {
+               bb_simple_perror_msg(file);
+               return FALSE;
+       }
 
-                               break;
+       bufPtr = bufBase;
+       bufUsed = 0;
+       lineCount = 0;
+       charCount = 0;
+       cc = 0;
 
-                       case 's':
-                               subCommand(cp, num1, num2);
-                               break;
+       printf("\"%s\", ", file);
+       fflush_all();
 
-                       case 'w':
-                               if (*cp && !isblank(*cp)) {
-                                       bb_error_msg("bad write command");
-                                       break;
-                               }
+       do {
+               cp = memchr(bufPtr, '\n', bufUsed);
 
-                               while (isblank(*cp))
-                                       cp++;
+               if (cp) {
+                       len = (cp - bufPtr) + 1;
+                       if (!insertLine(num, bufPtr, len)) {
+                               close(fd);
+                               return FALSE;
+                       }
+                       bufPtr += len;
+                       bufUsed -= len;
+                       charCount += len;
+                       lineCount++;
+                       num++;
+                       continue;
+               }
 
-                               if (!have1) {
-                                       num1 = 1;
-                                       num2 = lastNum;
-                               }
+               if (bufPtr != bufBase) {
+                       memcpy(bufBase, bufPtr, bufUsed);
+                       bufPtr = bufBase + bufUsed;
+               }
 
-                               if (*cp == '\0')
-                                       cp = fileName;
+               if (bufUsed >= bufSize) {
+                       len = (bufSize * 3) / 2;
+                       cp = xrealloc(bufBase, len);
+                       bufBase = cp;
+                       bufPtr = bufBase + bufUsed;
+                       bufSize = len;
+               }
 
-                               if (cp == NULL) {
-                                       bb_error_msg("no file name specified");
-                                       break;
-                               }
+               cc = safe_read(fd, bufPtr, bufSize - bufUsed);
+               bufUsed += cc;
+               bufPtr = bufBase;
+       } while (cc > 0);
 
-                               writeLines(cp, num1, num2);
-                               break;
+       if (cc < 0) {
+               bb_simple_perror_msg(file);
+               close(fd);
+               return FALSE;
+       }
 
-                       case 'z':
-                               switch (*cp) {
-                               case '-':
-                                       printLines(curNum-21, curNum, FALSE);
-                                       break;
-                               case '.':
-                                       printLines(curNum-11, curNum+10, FALSE);
-                                       break;
-                               default:
-                                       printLines(curNum, curNum+21, FALSE);
-                                       break;
-                               }
-                               break;
+       if (bufUsed) {
+               if (!insertLine(num, bufPtr, bufUsed)) {
+                       close(fd);
+                       return -1;
+               }
+               lineCount++;
+               charCount += bufUsed;
+       }
 
-                       case '.':
-                               if (have1) {
-                                       bb_error_msg("no arguments allowed");
-                                       break;
-                               }
+       close(fd);
 
-                               printLines(curNum, curNum, FALSE);
-                               break;
+       printf("%d lines%s, %d chars\n", lineCount,
+               (bufUsed ? " (incomplete)" : ""), charCount);
 
-                       case '-':
-                               if (setCurNum(curNum - 1))
-                                       printLines(curNum, curNum, FALSE);
+       return TRUE;
+}
 
-                               break;
+/*
+ * Write the specified lines out to the specified file.
+ * Returns TRUE if successful, or FALSE on an error with a message output.
+ */
+static int writeLines(const char *file, int num1, int num2)
+{
+       LINE *lp;
+       int fd, lineCount, charCount;
 
-                       case '=':
-                               printf("%d\n", num1);
-                               break;
+       if (bad_nums(num1, num2, "write"))
+               return FALSE;
 
-                       case '\0':
-                               if (have1) {
-                                       printLines(num2, num2, FALSE);
-                                       break;
-                               }
+       lineCount = 0;
+       charCount = 0;
 
-                               if (setCurNum(curNum + 1))
-                                       printLines(curNum, curNum, FALSE);
+       fd = creat(file, 0666);
+       if (fd < 0) {
+               bb_simple_perror_msg(file);
+               return FALSE;
+       }
 
-                               break;
+       printf("\"%s\", ", file);
+       fflush_all();
 
-                       default:
-                               bb_error_msg("unimplemented command");
-                               break;
+       lp = findLine(num1);
+       if (lp == NULL) {
+               close(fd);
+               return FALSE;
+       }
+
+       while (num1++ <= num2) {
+               if (full_write(fd, lp->data, lp->len) != lp->len) {
+                       bb_simple_perror_msg(file);
+                       close(fd);
+                       return FALSE;
+               }
+               charCount += lp->len;
+               lineCount++;
+               lp = lp->next;
+       }
+
+       if (close(fd) < 0) {
+               bb_simple_perror_msg(file);
+               return FALSE;
+       }
+
+       printf("%d lines, %d chars\n", lineCount, charCount);
+       return TRUE;
+}
+
+/*
+ * Print lines in a specified range.
+ * The last line printed becomes the current line.
+ * If expandFlag is TRUE, then the line is printed specially to
+ * show magic characters.
+ */
+static int printLines(int num1, int num2, int expandFlag)
+{
+       const LINE *lp;
+       const char *cp;
+       int ch, count;
+
+       if (bad_nums(num1, num2, "print"))
+               return FALSE;
+
+       lp = findLine(num1);
+       if (lp == NULL)
+               return FALSE;
+
+       while (num1 <= num2) {
+               if (!expandFlag) {
+                       write(STDOUT_FILENO, lp->data, lp->len);
+                       setCurNum(num1++);
+                       lp = lp->next;
+                       continue;
+               }
+
+               /*
+                * Show control characters and characters with the
+                * high bit set specially.
+                */
+               cp = lp->data;
+               count = lp->len;
+
+               if ((count > 0) && (cp[count - 1] == '\n'))
+                       count--;
+
+               while (count-- > 0) {
+                       ch = (unsigned char) *cp++;
+                       fputc_printable(ch | PRINTABLE_META, stdout);
                }
+
+               fputs("$\n", stdout);
+
+               setCurNum(num1++);
+               lp = lp->next;
        }
+
+       return TRUE;
 }
 
+/*
+ * Delete lines from the given range.
+ */
+static void deleteLines(int num1, int num2)
+{
+       LINE *lp, *nlp, *plp;
+       int count;
+
+       if (bad_nums(num1, num2, "delete"))
+               return;
+
+       lp = findLine(num1);
+       if (lp == NULL)
+               return;
+
+       if ((curNum >= num1) && (curNum <= num2)) {
+               if (num2 < lastNum)
+                       setCurNum(num2 + 1);
+               else if (num1 > 1)
+                       setCurNum(num1 - 1);
+               else
+                       curNum = 0;
+       }
+
+       count = num2 - num1 + 1;
+       if (curNum > num2)
+               curNum -= count;
+       lastNum -= count;
+
+       while (count-- > 0) {
+               nlp = lp->next;
+               plp = lp->prev;
+               plp->next = nlp;
+               nlp->prev = plp;
+               free(lp);
+               lp = nlp;
+       }
+
+       dirty = TRUE;
+}
 
 /*
  * Do the substitute command.
  * The current line is set to the last substitution done.
  */
-static void subCommand(const char * cmd, int num1, int num2)
+static void subCommand(const char *cmd, int num1, int num2)
 {
        char *cp, *oldStr, *newStr, buf[USERSIZE];
        int delim, oldLen, newLen, deltaLen, offset;
        LINE *lp, *nlp;
        int globalFlag, printFlag, didSub, needPrint;
 
-       if ((num1 < 1) || (num2 > lastNum) || (num1 > num2)) {
-               bb_error_msg("bad line range for substitute");
+       if (bad_nums(num1, num2, "substitute"))
                return;
-       }
 
        globalFlag = FALSE;
        printFlag = FALSE;
@@ -394,7 +637,6 @@ static void subCommand(const char * cmd, int num1, int num2)
        oldStr = cp;
 
        cp = strchr(cp, delim);
-
        if (cp == NULL) {
                bb_error_msg("missing 2nd delimiter for substitute");
                return;
@@ -414,11 +656,9 @@ static void subCommand(const char * cmd, int num1, int num2)
                case 'g':
                        globalFlag = TRUE;
                        break;
-
                case 'p':
                        printFlag = TRUE;
                        break;
-
                default:
                        bb_error_msg("unknown option for substitute");
                        return;
@@ -429,7 +669,6 @@ static void subCommand(const char * cmd, int num1, int num2)
                        bb_error_msg("no previous search string");
                        return;
                }
-
                oldStr = searchString;
        }
 
@@ -437,7 +676,6 @@ static void subCommand(const char * cmd, int num1, int num2)
                strcpy(searchString, oldStr);
 
        lp = findLine(num1);
-
        if (lp == NULL)
                return;
 
@@ -455,11 +693,9 @@ static void subCommand(const char * cmd, int num1, int num2)
                                printLines(num1, num1, FALSE);
                                needPrint = FALSE;
                        }
-
                        offset = 0;
                        lp = lp->next;
                        num1++;
-
                        continue;
                }
 
@@ -473,7 +709,6 @@ static void subCommand(const char * cmd, int num1, int num2)
                 */
                if (deltaLen <= 0) {
                        memcpy(&lp->data[offset], newStr, newLen);
-
                        if (deltaLen) {
                                memcpy(&lp->data[offset + newLen],
                                        &lp->data[offset + oldLen],
@@ -481,41 +716,29 @@ static void subCommand(const char * cmd, int num1, int num2)
 
                                lp->len += deltaLen;
                        }
-
                        offset += newLen;
-
                        if (globalFlag)
                                continue;
-
                        if (needPrint) {
                                printLines(num1, num1, FALSE);
                                needPrint = FALSE;
                        }
-
                        lp = lp->next;
                        num1++;
-
                        continue;
                }
 
                /*
                 * The new string is larger, so allocate a new line
-                * structure and use that.  Link it in in place of
+                * structure and use that.  Link it in place of
                 * the old line structure.
                 */
-               nlp = (LINE *) malloc(sizeof(LINE) + lp->len + deltaLen);
-
-               if (nlp == NULL) {
-                       bb_error_msg("cannot get memory for line");
-                       return;
-               }
+               nlp = xmalloc(sizeof(LINE) + lp->len + deltaLen);
 
                nlp->len = lp->len + deltaLen;
 
                memcpy(nlp->data, lp->data, offset);
-
                memcpy(&nlp->data[offset], newStr, newLen);
-
                memcpy(&nlp->data[offset + newLen],
                        &lp->data[offset + oldLen],
                        lp->len - offset - oldLen);
@@ -549,690 +772,245 @@ static void subCommand(const char * cmd, int num1, int num2)
                bb_error_msg("no substitutions found for \"%s\"", oldStr);
 }
 
-
-/*
- * Search a line for the specified string starting at the specified
- * offset in the line.  Returns the offset of the found string, or -1.
- */
-static int findString( const LINE * lp, const char * str, int len, int offset)
-{
-       int left;
-       const char *cp, *ncp;
-
-       cp = &lp->data[offset];
-       left = lp->len - offset;
-
-       while (left >= len) {
-               ncp = memchr(cp, *str, left);
-
-               if (ncp == NULL)
-                       return -1;
-
-               left -= (ncp - cp);
-
-               if (left < len)
-                       return -1;
-
-               cp = ncp;
-
-               if (memcmp(cp, str, len) == 0)
-                       return (cp - lp->data);
-
-               cp++;
-               left--;
-       }
-
-       return -1;
-}
-
-
 /*
- * Add lines which are typed in by the user.
- * The lines are inserted just before the specified line number.
- * The lines are terminated by a line containing a single dot (ugly!),
- * or by an end of file.
+ * Read commands until we are told to stop.
  */
-static void addLines(int num)
+static void doCommands(void)
 {
-       int len;
-       char buf[USERSIZE + 1];
-
-       while (fgets(buf, sizeof(buf), stdin)) {
-               if ((buf[0] == '.') && (buf[1] == '\n') && (buf[2] == '\0'))
+       while (TRUE) {
+               char buf[USERSIZE];
+               const char *cp;
+               int len;
+               int n, num1, num2;
+               smallint h, have1, have2;
+
+               /* Returns:
+                * -1 on read errors or EOF, or on bare Ctrl-D.
+                * 0  on ctrl-C,
+                * >0 length of input string, including terminating '\n'
+                */
+               len = read_line_input(NULL, ": ", buf, sizeof(buf), /*timeout*/ -1);
+               if (len <= 0)
                        return;
+               while (len && isspace(buf[--len]))
+                       buf[len] = '\0';
 
-               len = strlen(buf);
-
-               if (len == 0)
-                       return;
+               if ((curNum == 0) && (lastNum > 0)) {
+                       curNum = 1;
+                       curLine = lines.next;
+               }
 
-               if (buf[len - 1] != '\n') {
-                       bb_error_msg("line too long");
-                       do {
-                               len = fgetc(stdin);
-                       } while ((len != EOF) && (len != '\n'));
-                       return;
+               have1 = FALSE;
+               have2 = FALSE;
+               /* Don't pass &haveN, &numN to getNum() since this forces
+                * compiler to keep them on stack, not in registers,
+                * which is usually quite suboptimal.
+                * Using intermediate variables shrinks code by ~150 bytes.
+                */
+               cp = getNum(skip_whitespace(buf), &h, &n);
+               if (!cp)
+                       continue;
+               have1 = h;
+               num1 = n;
+               cp = skip_whitespace(cp);
+               if (*cp == ',') {
+                       cp = getNum(cp + 1, &h, &n);
+                       if (!cp)
+                               continue;
+                       num2 = n;
+                       if (!have1)
+                               num1 = 1;
+                       if (!h)
+                               num2 = lastNum;
+                       have1 = TRUE;
+                       have2 = TRUE;
                }
+               if (!have1)
+                       num1 = curNum;
+               if (!have2)
+                       num2 = num1;
 
-               if (!insertLine(num++, buf, len))
-                       return;
-       }
-}
+               switch (*cp++) {
+               case 'a':
+                       addLines(num1 + 1);
+                       break;
 
+               case 'c':
+                       deleteLines(num1, num2);
+                       addLines(num1);
+                       break;
 
-/*
- * Parse a line number argument if it is present.  This is a sum
- * or difference of numbers, '.', '$', 'x, or a search string.
- * Returns TRUE if successful (whether or not there was a number).
- * Returns FALSE if there was a parsing error, with a message output.
- * Whether there was a number is returned indirectly, as is the number.
- * The character pointer which stopped the scan is also returned.
- */
-static int getNum(const char **retcp, int *retHaveNum, int *retNum)
-{
-       const char *cp;
-       char *endStr, str[USERSIZE];
-       int haveNum, value, num, sign;
+               case 'd':
+                       deleteLines(num1, num2);
+                       break;
 
-       cp = *retcp;
-       haveNum = FALSE;
-       value = 0;
-       sign = 1;
+               case 'f':
+                       if (*cp != '\0' && *cp != ' ') {
+                               bb_error_msg("bad file command");
+                               break;
+                       }
+                       cp = skip_whitespace(cp);
+                       if (*cp == '\0') {
+                               if (fileName)
+                                       printf("\"%s\"\n", fileName);
+                               else
+                                       puts("No file name");
+                               break;
+                       }
+                       free(fileName);
+                       fileName = xstrdup(cp);
+                       break;
 
-       while (TRUE) {
-               while (isblank(*cp))
-                       cp++;
+               case 'i':
+                       if (!have1 && lastNum == 0)
+                               num1 = 1;
+                       addLines(num1);
+                       break;
 
-               switch (*cp) {
-                       case '.':
-                               haveNum = TRUE;
-                               num = curNum;
-                               cp++;
+               case 'k':
+                       cp = skip_whitespace(cp);
+                       if ((unsigned)(*cp - 'a') >= 26 || cp[1]) {
+                               bb_error_msg("bad mark name");
                                break;
+                       }
+                       marks[(unsigned)(*cp - 'a')] = num2;
+                       break;
 
-                       case '$':
-                               haveNum = TRUE;
-                               num = lastNum;
-                               cp++;
-                               break;
+               case 'l':
+                       printLines(num1, num2, TRUE);
+                       break;
 
-                       case '\'':
-                               cp++;
+               case 'p':
+                       printLines(num1, num2, FALSE);
+                       break;
 
-                               if ((*cp < 'a') || (*cp > 'z')) {
-                                       bb_error_msg("bad mark name");
-                                       return FALSE;
-                               }
+               case 'q':
+                       cp = skip_whitespace(cp);
+                       if (have1 || *cp) {
+                               bb_error_msg("bad quit command");
+                               break;
+                       }
+                       if (!dirty)
+                               return;
+                       len = read_line_input(NULL, "Really quit? ", buf, 16, /*timeout*/ -1);
+                       /* read error/EOF - no way to continue */
+                       if (len < 0)
+                               return;
+                       cp = skip_whitespace(buf);
+                       if ((*cp | 0x20) == 'y') /* Y or y */
+                               return;
+                       break;
 
-                               haveNum = TRUE;
-                               num = marks[*cp++ - 'a'];
+               case 'r':
+                       if (*cp != '\0' && *cp != ' ') {
+                               bb_error_msg("bad read command");
                                break;
+                       }
+                       cp = skip_whitespace(cp);
+                       if (*cp == '\0') {
+                               bb_error_msg("no file name");
+                               break;
+                       }
+                       if (!have1)
+                               num1 = lastNum;
+                       if (readLines(cp, num1 + 1))
+                               break;
+                       if (fileName == NULL)
+                               fileName = xstrdup(cp);
+                       break;
 
-                       case '/':
-                               strcpy(str, ++cp);
-                               endStr = strchr(str, '/');
+               case 's':
+                       subCommand(cp, num1, num2);
+                       break;
 
-                               if (endStr) {
-                                       *endStr++ = '\0';
-                                       cp += (endStr - str);
+               case 'w':
+                       if (*cp != '\0' && *cp != ' ') {
+                               bb_error_msg("bad write command");
+                               break;
+                       }
+                       cp = skip_whitespace(cp);
+                       if (*cp == '\0') {
+                               cp = fileName;
+                               if (!cp) {
+                                       bb_error_msg("no file name specified");
+                                       break;
                                }
-                               else
-                                       cp = "";
-
-                               num = searchLines(str, curNum, lastNum);
-
-                               if (num == 0)
-                                       return FALSE;
+                       }
+                       if (!have1) {
+                               num1 = 1;
+                               num2 = lastNum;
+                               dirty = FALSE;
+                       }
+                       writeLines(cp, num1, num2);
+                       break;
 
-                               haveNum = TRUE;
+               case 'z':
+                       switch (*cp) {
+                       case '-':
+                               printLines(curNum - 21, curNum, FALSE);
+                               break;
+                       case '.':
+                               printLines(curNum - 11, curNum + 10, FALSE);
                                break;
-
                        default:
-                               if (!isdigit(*cp)) {
-                                       *retcp = cp;
-                                       *retHaveNum = haveNum;
-                                       *retNum = value;
-                                       return TRUE;
-                               }
-
-                               num = 0;
-
-                               while (isdigit(*cp))
-                                       num = num * 10 + *cp++ - '0';
-
-                               haveNum = TRUE;
+                               printLines(curNum, curNum + 21, FALSE);
                                break;
-               }
-
-               value += num * sign;
-
-               while (isblank(*cp))
-                       cp++;
+                       }
+                       break;
 
-               switch (*cp) {
-                       case '-':
-                               sign = -1;
-                               cp++;
+               case '.':
+                       if (have1) {
+                               bb_error_msg("no arguments allowed");
                                break;
+                       }
+                       printLines(curNum, curNum, FALSE);
+                       break;
 
-                       case '+':
-                               sign = 1;
-                               cp++;
+               case '-':
+                       if (setCurNum(curNum - 1))
+                               printLines(curNum, curNum, FALSE);
+                       break;
+
+               case '=':
+                       printf("%d\n", num1);
+                       break;
+               case '\0':
+                       if (have1) {
+                               printLines(num2, num2, FALSE);
                                break;
+                       }
+                       if (setCurNum(curNum + 1))
+                               printLines(curNum, curNum, FALSE);
+                       break;
 
-                       default:
-                               *retcp = cp;
-                               *retHaveNum = haveNum;
-                               *retNum = value;
-                               return TRUE;
+               default:
+                       bb_error_msg("unimplemented command");
+                       break;
                }
        }
 }
 
-
-/*
- * Initialize everything for editing.
- */
-static int initEdit(void)
+int ed_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
+int ed_main(int argc UNUSED_PARAM, char **argv)
 {
-       int i;
+       INIT_G();
 
        bufSize = INITBUF_SIZE;
-       bufBase = malloc(bufSize);
-
-       if (bufBase == NULL) {
-               bb_error_msg("no memory for buffer");
-               return FALSE;
-       }
-
+       bufBase = xmalloc(bufSize);
        bufPtr = bufBase;
-       bufUsed = 0;
-
        lines.next = &lines;
        lines.prev = &lines;
 
-       curLine = NULL;
-       curNum = 0;
-       lastNum = 0;
-       dirty = FALSE;
-       fileName = NULL;
-       searchString[0] = '\0';
-
-       for (i = 0; i < 26; i++)
-               marks[i] = 0;
-
-       return TRUE;
-}
-
-
-/*
- * Finish editing.
- */
-static void termEdit(void)
-{
-       if (bufBase)
-               free(bufBase);
-
-       bufBase = NULL;
-       bufPtr = NULL;
-       bufSize = 0;
-       bufUsed = 0;
-
-       if (fileName)
-               free(fileName);
-
-       fileName = NULL;
-
-       searchString[0] = '\0';
-
-       if (lastNum)
-               deleteLines(1, lastNum);
-
-       lastNum = 0;
-       curNum = 0;
-       curLine = NULL;
-}
-
-
-/*
- * Read lines from a file at the specified line number.
- * Returns TRUE if the file was successfully read.
- */
-static int readLines(const char * file, int num)
-{
-       int fd, cc;
-       int len, lineCount, charCount;
-       char *cp;
-
-       if ((num < 1) || (num > lastNum + 1)) {
-               bb_error_msg("bad line for read");
-               return FALSE;
-       }
-
-       fd = open(file, 0);
-
-       if (fd < 0) {
-               perror(file);
-               return FALSE;
+       if (argv[1]) {
+               fileName = xstrdup(argv[1]);
+               if (!readLines(fileName, 1)) {
+                       return EXIT_SUCCESS;
+               }
+               if (lastNum)
+                       setCurNum(1);
+               dirty = FALSE;
        }
 
-       bufPtr = bufBase;
-       bufUsed = 0;
-       lineCount = 0;
-       charCount = 0;
-       cc = 0;
-
-       printf("\"%s\", ", file);
-       fflush(stdout);
-
-       do {
-               cp = memchr(bufPtr, '\n', bufUsed);
-
-               if (cp) {
-                       len = (cp - bufPtr) + 1;
-
-                       if (!insertLine(num, bufPtr, len)) {
-                               close(fd);
-                               return FALSE;
-                       }
-
-                       bufPtr += len;
-                       bufUsed -= len;
-                       charCount += len;
-                       lineCount++;
-                       num++;
-
-                       continue;
-               }
-
-               if (bufPtr != bufBase) {
-                       memcpy(bufBase, bufPtr, bufUsed);
-                       bufPtr = bufBase + bufUsed;
-               }
-
-               if (bufUsed >= bufSize) {
-                       len = (bufSize * 3) / 2;
-                       cp = realloc(bufBase, len);
-
-                       if (cp == NULL) {
-                               bb_error_msg("no memory for buffer");
-                               close(fd);
-                               return FALSE;
-                       }
-
-                       bufBase = cp;
-                       bufPtr = bufBase + bufUsed;
-                       bufSize = len;
-               }
-
-               cc = read(fd, bufPtr, bufSize - bufUsed);
-               bufUsed += cc;
-               bufPtr = bufBase;
-
-       } while (cc > 0);
-
-       if (cc < 0) {
-               perror(file);
-               close(fd);
-               return FALSE;
-       }
-
-       if (bufUsed) {
-               if (!insertLine(num, bufPtr, bufUsed)) {
-                       close(fd);
-                       return -1;
-               }
-
-               lineCount++;
-               charCount += bufUsed;
-       }
-
-       close(fd);
-
-       printf("%d lines%s, %d chars\n", lineCount,
-               (bufUsed ? " (incomplete)" : ""), charCount);
-
-       return TRUE;
-}
-
-
-/*
- * Write the specified lines out to the specified file.
- * Returns TRUE if successful, or FALSE on an error with a message output.
- */
-static int writeLines(const char * file, int num1, int num2)
-{
-       LINE *lp;
-       int fd, lineCount, charCount;
-
-       if ((num1 < 1) || (num2 > lastNum) || (num1 > num2)) {
-               bb_error_msg("bad line range for write");
-               return FALSE;
-       }
-
-       lineCount = 0;
-       charCount = 0;
-
-       fd = creat(file, 0666);
-
-       if (fd < 0) {
-               perror(file);
-               return FALSE;
-       }
-
-       printf("\"%s\", ", file);
-       fflush(stdout);
-
-       lp = findLine(num1);
-
-       if (lp == NULL) {
-               close(fd);
-               return FALSE;
-       }
-
-       while (num1++ <= num2) {
-               if (write(fd, lp->data, lp->len) != lp->len) {
-                       perror(file);
-                       close(fd);
-                       return FALSE;
-               }
-
-               charCount += lp->len;
-               lineCount++;
-               lp = lp->next;
-       }
-
-       if (close(fd) < 0) {
-               perror(file);
-               return FALSE;
-       }
-
-       printf("%d lines, %d chars\n", lineCount, charCount);
-       return TRUE;
-}
-
-
-/*
- * Print lines in a specified range.
- * The last line printed becomes the current line.
- * If expandFlag is TRUE, then the line is printed specially to
- * show magic characters.
- */
-static int printLines(int num1, int num2, int expandFlag)
-{
-       const LINE *lp;
-       const char *cp;
-       int ch, count;
-
-       if ((num1 < 1) || (num2 > lastNum) || (num1 > num2)) {
-               bb_error_msg("bad line range for print");
-               return FALSE;
-       }
-
-       lp = findLine(num1);
-
-       if (lp == NULL)
-               return FALSE;
-
-       while (num1 <= num2) {
-               if (!expandFlag) {
-                       write(1, lp->data, lp->len);
-                       setCurNum(num1++);
-                       lp = lp->next;
-
-                       continue;
-               }
-
-               /*
-                * Show control characters and characters with the
-                * high bit set specially.
-                */
-               cp = lp->data;
-               count = lp->len;
-
-               if ((count > 0) && (cp[count - 1] == '\n'))
-                       count--;
-
-               while (count-- > 0) {
-                       ch = *cp++;
-
-                       if (ch & 0x80) {
-                               fputs("M-", stdout);
-                               ch &= 0x7f;
-                       }
-
-                       if (ch < ' ') {
-                               fputc('^', stdout);
-                               ch += '@';
-                       }
-
-                       if (ch == 0x7f) {
-                               fputc('^', stdout);
-                               ch = '?';
-                       }
-
-                       fputc(ch, stdout);
-               }
-
-               fputs("$\n", stdout);
-
-               setCurNum(num1++);
-               lp = lp->next;
-       }
-
-       return TRUE;
-}
-
-
-/*
- * Insert a new line with the specified text.
- * The line is inserted so as to become the specified line,
- * thus pushing any existing and further lines down one.
- * The inserted line is also set to become the current line.
- * Returns TRUE if successful.
- */
-static int insertLine(int num, const char * data, int len)
-{
-       LINE *newLp, *lp;
-
-       if ((num < 1) || (num > lastNum + 1)) {
-               bb_error_msg("inserting at bad line number");
-               return FALSE;
-       }
-
-       newLp = malloc(sizeof(LINE) + len - 1);
-
-       if (newLp == NULL) {
-               bb_error_msg("failed to allocate memory for line");
-               return FALSE;
-       }
-
-       memcpy(newLp->data, data, len);
-       newLp->len = len;
-
-       if (num > lastNum)
-               lp = &lines;
-       else {
-               lp = findLine(num);
-
-               if (lp == NULL) {
-                       free((char *) newLp);
-                       return FALSE;
-               }
-       }
-
-       newLp->next = lp;
-       newLp->prev = lp->prev;
-       lp->prev->next = newLp;
-       lp->prev = newLp;
-
-       lastNum++;
-       dirty = TRUE;
-       return setCurNum(num);
-}
-
-
-/*
- * Delete lines from the given range.
- */
-static int deleteLines(int num1, int num2)
-{
-       LINE *lp, *nlp, *plp;
-       int count;
-
-       if ((num1 < 1) || (num2 > lastNum) || (num1 > num2)) {
-               bb_error_msg("bad line numbers for delete");
-               return FALSE;
-       }
-
-       lp = findLine(num1);
-
-       if (lp == NULL)
-               return FALSE;
-
-       if ((curNum >= num1) && (curNum <= num2)) {
-               if (num2 < lastNum)
-                       setCurNum(num2 + 1);
-               else if (num1 > 1)
-                       setCurNum(num1 - 1);
-               else
-                       curNum = 0;
-       }
-
-       count = num2 - num1 + 1;
-
-       if (curNum > num2)
-               curNum -= count;
-
-       lastNum -= count;
-
-       while (count-- > 0) {
-               nlp = lp->next;
-               plp = lp->prev;
-               plp->next = nlp;
-               nlp->prev = plp;
-               lp->next = NULL;
-               lp->prev = NULL;
-               lp->len = 0;
-               free(lp);
-               lp = nlp;
-       }
-
-       dirty = TRUE;
-
-       return TRUE;
-}
-
-
-/*
- * Search for a line which contains the specified string.
- * If the string is NULL, then the previously searched for string
- * is used.  The currently searched for string is saved for future use.
- * Returns the line number which matches, or 0 if there was no match
- * with an error printed.
- */
-static int searchLines(const char *str, int num1, int num2)
-{
-       const LINE *lp;
-       int len;
-
-       if ((num1 < 1) || (num2 > lastNum) || (num1 > num2)) {
-               bb_error_msg("bad line numbers for search");
-               return 0;
-       }
-
-       if (*str == '\0') {
-               if (searchString[0] == '\0') {
-                       bb_error_msg("no previous search string");
-                       return 0;
-               }
-
-               str = searchString;
-       }
-
-       if (str != searchString)
-               strcpy(searchString, str);
-
-       len = strlen(str);
-
-       lp = findLine(num1);
-
-       if (lp == NULL)
-               return 0;
-
-       while (num1 <= num2) {
-               if (findString(lp, str, len, 0) >= 0)
-                       return num1;
-
-               num1++;
-               lp = lp->next;
-       }
-
-       bb_error_msg("cannot find string \"%s\"", str);
-       return 0;
-}
-
-
-/*
- * Return a pointer to the specified line number.
- */
-static LINE *findLine(int num)
-{
-       LINE *lp;
-       int lnum;
-
-       if ((num < 1) || (num > lastNum)) {
-               bb_error_msg("line number %d does not exist", num);
-               return NULL;
-       }
-
-       if (curNum <= 0) {
-               curNum = 1;
-               curLine = lines.next;
-       }
-
-       if (num == curNum)
-               return curLine;
-
-       lp = curLine;
-       lnum = curNum;
-
-       if (num < (curNum / 2)) {
-               lp = lines.next;
-               lnum = 1;
-       }
-       else if (num > ((curNum + lastNum) / 2)) {
-               lp = lines.prev;
-               lnum = lastNum;
-       }
-
-       while (lnum < num) {
-               lp = lp->next;
-               lnum++;
-       }
-
-       while (lnum > num) {
-               lp = lp->prev;
-               lnum--;
-       }
-       return lp;
-}
-
-
-/*
- * Set the current line number.
- * Returns TRUE if successful.
- */
-static int setCurNum(int num)
-{
-       LINE *lp;
-
-       lp = findLine(num);
-
-       if (lp == NULL)
-               return FALSE;
-
-       curNum = num;
-       curLine = lp;
-       return TRUE;
+       doCommands();
+       return EXIT_SUCCESS;
 }