Thought of another janitorial item for the list.
[oweals/busybox.git] / grep.c
diff --git a/grep.c b/grep.c
index 320655bf4eb71b1c17f32a6d1d642c40acec9890..475b4ef212c1e79950609fc990331587df785638 100644 (file)
--- a/grep.c
+++ b/grep.c
 #include <errno.h>
 #include "busybox.h"
 
-extern void xregcomp(regex_t *preg, const char *regex, int cflags);
 
 extern int optind; /* in unistd.h */
 extern int errno;  /* for use with strerror() */
+extern void xregcomp(regex_t *preg, const char *regex, int cflags); /* in busybox.h */
 
 /* options */
 static int ignore_case       = 0;
@@ -42,22 +42,32 @@ static int be_quiet          = 0;
 static int invert_search     = 0;
 static int suppress_err_msgs = 0;
 
-/* globals */
+#ifdef BB_FEATURE_GREP_CONTEXT
+extern char *optarg; /* in getopt.h */
+static int lines_before      = 0;
+static int lines_after       = 0;
+static char **before_buf     = NULL;
+static int last_line_printed = 0;
+#endif /* BB_FEATURE_GREP_CONTEXT */
+
+/* globals used internally */
 static regex_t regex; /* storage space for compiled regular expression */
 static int matched; /* keeps track of whether we ever matched */
 static char *cur_file = NULL; /* the current file we are reading */
 
-
-static void print_matched_line(char *line, int linenum)
+static void print_line(const char *line, int linenum, char decoration)
 {
-       if (print_count_only)
-               return;
-
+#ifdef BB_FEATURE_GREP_CONTEXT
+       /* possibly print the little '--' seperator */
+       if (last_line_printed && last_line_printed < linenum - 1) {
+               puts("--");
+       }
+       last_line_printed = linenum;
+#endif
        if (print_filename)
-               printf("%s:", cur_file);
+               printf("%s%c", cur_file, decoration);
        if (print_line_num)
-               printf("%i:", linenum);
-
+               printf("%i%c", linenum, decoration);
        puts(line);
 }
 
@@ -67,13 +77,24 @@ static void grep_file(FILE *file)
        int ret;
        int linenum = 0;
        int nmatches = 0;
+#ifdef BB_FEATURE_GREP_CONTEXT
+       int print_n_lines_after = 0;
+       int curpos = 0; /* track where we are in the circular 'before' buffer */
+       int idx = 0; /* used for iteration through the circular buffer */
+#endif /* BB_FEATURE_GREP_CONTEXT */ 
 
        while ((line = get_line_from_file(file)) != NULL) {
-               if (line[strlen(line)-1] == '\n')
-                       line[strlen(line)-1] = '\0';
+               chomp(line);
                linenum++;
+
+               /*
+                * test for a postitive-assertion match (regexec returns success (0)
+                * and the user did not specify invert search), or a negative-assertion
+                * match (regexec returns failure (REG_NOMATCH) and the user specified
+                * invert search)
+                */
                ret = regexec(&regex, line, 0, NULL, 0);
-               if (ret == 0 && !invert_search) { /* match */
+               if ((ret == 0 && !invert_search) || (ret == REG_NOMATCH && invert_search)) {
 
                        /* if we found a match but were told to be quiet, stop here and
                         * return success */
@@ -82,20 +103,62 @@ static void grep_file(FILE *file)
                                exit(0);
                        }
 
+                       /* otherwise, keep track of matches and print the matched line */
                        nmatches++;
-                       print_matched_line(line, linenum);
+                       if (!print_count_only) {
+#ifdef BB_FEATURE_GREP_CONTEXT
+                               int prevpos = (curpos == 0) ? lines_before - 1 : curpos - 1;
 
+                               /* if we were told to print 'before' lines and there is at least
+                                * one line in the circular buffer, print them */
+                               if (lines_before && before_buf[prevpos] != NULL)
+                               {
+                                       int first_buf_entry_line_num = linenum - lines_before;
+
+                                       /* advance to the first entry in the circular buffer, and
+                                        * figure out the line number is of the first line in the
+                                        * buffer */
+                                       idx = curpos;
+                                       while (before_buf[idx] == NULL) {
+                                               idx = (idx + 1) % lines_before;
+                                               first_buf_entry_line_num++;
+                                       }
+
+                                       /* now print each line in the buffer, clearing them as we go */
+                                       while (before_buf[idx] != NULL) {
+                                               print_line(before_buf[idx], first_buf_entry_line_num, '-');
+                                               free(before_buf[idx]);
+                                               before_buf[idx] = NULL;
+                                               idx = (idx + 1) % lines_before;
+                                               first_buf_entry_line_num++;
+                                       }
+
+                               }
+
+                               /* make a note that we need to print 'after' lines */
+                               print_n_lines_after = lines_after;
+#endif /* BB_FEATURE_GREP_CONTEXT */ 
+                               print_line(line, linenum, ':');
+                       }
                }
-               else if (ret == REG_NOMATCH && invert_search) {
-                       if (be_quiet) {
-                               regfree(&regex);
-                               exit(0);
+#ifdef BB_FEATURE_GREP_CONTEXT
+               else { /* no match */
+                       /* Add the line to the circular 'before' buffer */
+                       if(lines_before)
+                       {
+                               if(before_buf[curpos])
+                                       free(before_buf[curpos]);
+                               before_buf[curpos] = strdup(line);
+                               curpos = (curpos + 1) % lines_before;
                        }
-
-                       nmatches++;
-                       print_matched_line(line, linenum);
                }
 
+               /* if we need to print some context lines after the last match, do so */
+               if (print_n_lines_after && (last_line_printed != linenum)) {
+                       print_line(line, linenum, '-');
+                       print_n_lines_after--;
+               }
+#endif /* BB_FEATURE_GREP_CONTEXT */ 
                free(line);
        }
 
@@ -106,7 +169,7 @@ static void grep_file(FILE *file)
                printf("%i\n", nmatches);
        }
 
-       /* record if we matched */
+       /* remember if we matched */
        if (nmatches != 0)
                matched = 1;
 }
@@ -115,9 +178,16 @@ extern int grep_main(int argc, char **argv)
 {
        int opt;
        int reflags;
+#ifdef BB_FEATURE_GREP_CONTEXT
+       char *junk;
+#endif
 
        /* do normal option parsing */
-       while ((opt = getopt(argc, argv, "iHhnqvsc")) > 0) {
+       while ((opt = getopt(argc, argv, "iHhnqvsc"
+#ifdef BB_FEATURE_GREP_CONTEXT
+"A:B:C:"
+#endif
+)) > 0) {
                switch (opt) {
                        case 'i':
                                ignore_case++;
@@ -143,12 +213,40 @@ extern int grep_main(int argc, char **argv)
                        case 'c':
                                print_count_only++;
                                break;
+#ifdef BB_FEATURE_GREP_CONTEXT
+                       case 'A':
+                               lines_after = strtoul(optarg, &junk, 10);
+                               if(*junk != '\0')
+                                       error_msg_and_die("invalid context length argument");
+                               break;
+                       case 'B':
+                               lines_before = strtoul(optarg, &junk, 10);
+                               if(*junk != '\0')
+                                       error_msg_and_die("invalid context length argument");
+                               before_buf = (char **)calloc(lines_before, sizeof(char *));
+                               break;
+                       case 'C':
+                               lines_after = lines_before = strtoul(optarg, &junk, 10);
+                               if(*junk != '\0')
+                                       error_msg_and_die("invalid context length argument");
+                               before_buf = (char **)calloc(lines_before, sizeof(char *));
+                               break;
+#endif /* BB_FEATURE_GREP_CONTEXT */
                }
        }
 
        /* argv[optind] should be the regex pattern; no pattern, no worky */
        if (argv[optind] == NULL)
-               usage(grep_usage);
+               show_usage();
+
+       /* sanity check */
+       if (print_count_only || be_quiet) {
+               print_line_num = 0;
+#ifdef BB_FEATURE_GREP_CONTEXT
+               lines_before = 0;
+               lines_after = 0;
+#endif
+       }
 
        /* compile the regular expression
         * we're not going to mess with sub-expressions, and we need to
@@ -187,8 +285,5 @@ extern int grep_main(int argc, char **argv)
 
        regfree(&regex);
 
-       if (!matched)
-               return 1;
-
-       return 0;
+       return !matched; /* invert return value 0 = success, 1 = failed */
 }