coreutils/fold.c

   1 /* vi: set sw=4 ts=4: */
   2 /* fold -- wrap each input line to fit in specified width.
   3
   4    Written by David MacKenzie, djm@gnu.ai.mit.edu.
   5    Copyright (C) 91, 1995-2002 Free Software Foundation, Inc.
   6
   7    Modified for busybox based on coreutils v 5.0
   8    Copyright (C) 2003 Glenn McGrath <bug1@iinet.net.au>
   9
  10    Licensed under the GPL v2 or later, see the file LICENSE in this tarball.
  11 */
  12
  13 #include "libbb.h"
  14
  15 static unsigned long flags;
  16 #define FLAG_COUNT_BYTES        1
  17 #define FLAG_BREAK_SPACES       2
  18 #define FLAG_WIDTH                      4
  19
  20 /* Assuming the current column is COLUMN, return the column that
  21    printing C will move the cursor to.
  22    The first column is 0. */
  23
  24 static int adjust_column(int column, char c)
  25 {
  26         if (!(flags & FLAG_COUNT_BYTES)) {
  27                 if (c == '\b') {
  28                         if (column > 0)
  29                                 column--;
  30                 } else if (c == '\r')
  31                         column = 0;
  32                 else if (c == '\t')
  33                         column = column + 8 - column % 8;
  34                 else                    /* if (isprint (c)) */
  35                         column++;
  36         } else
  37                 column++;
  38         return column;
  39 }
  40
  41 int fold_main(int argc, char **argv);
  42 int fold_main(int argc, char **argv)
  43 {
  44         char *line_out = NULL;
  45         int allocated_out = 0;
  46         char *w_opt;
  47         int width = 80;
  48         int i;
  49         int errs = 0;
  50
  51         if (ENABLE_INCLUDE_SUSv2) {
  52                 /* Turn any numeric options into -w options.  */
  53                 for (i = 1; i < argc; i++) {
  54                         char const *a = argv[i];
  55
  56                         if (*a++ == '-') {
  57                                 if (*a == '-' && !a[1])
  58                                         break;
  59                                 if (isdigit(*a)) {
  60                                         argv[i] = xasprintf("-w%s", a);
  61                                 }
  62                         }
  63                 }
  64         }
  65
  66         flags = getopt32(argc, argv, "bsw:", &w_opt);
  67         if (flags & FLAG_WIDTH)
  68                 width = xatoul_range(w_opt, 1, 10000);
  69
  70         argv += optind;
  71         if (!*argv) {
  72                 *--argv = (char*)"-";
  73         }
  74
  75         do {
  76                 FILE *istream = fopen_or_warn_stdin(*argv);
  77                 int c;
  78                 int column = 0;         /* Screen column where next char will go. */
  79                 int offset_out = 0;     /* Index in `line_out' for next char. */
  80
  81                 if (istream == NULL) {
  82                         errs |= EXIT_FAILURE;
  83                         continue;
  84                 }
  85
  86                 while ((c = getc(istream)) != EOF) {
  87                         if (offset_out + 1 >= allocated_out) {
  88                                 allocated_out += 1024;
  89                                 line_out = xrealloc(line_out, allocated_out);
  90                         }
  91
  92                         if (c == '\n') {
  93                                 line_out[offset_out++] = c;
  94                                 fwrite(line_out, sizeof(char), (size_t) offset_out, stdout);
  95                                 column = offset_out = 0;
  96                                 continue;
  97                         }
  98  rescan:
  99                         column = adjust_column(column, c);
 100
 101                         if (column > width) {
 102                                 /* This character would make the line too long.
 103                                    Print the line plus a newline, and make this character
 104                                    start the next line. */
 105                                 if (flags & FLAG_BREAK_SPACES) {
 106                                         /* Look for the last blank. */
 107                                         int logical_end;
 108
 109                                         for (logical_end = offset_out - 1; logical_end >= 0; logical_end--) {
 110                                                 if (isblank(line_out[logical_end])) {
 111                                                         break;
 112                                                 }
 113                                         }
 114                                         if (logical_end >= 0) {
 115                                                 /* Found a blank.  Don't output the part after it. */
 116                                                 logical_end++;
 117                                                 fwrite(line_out, sizeof(char), (size_t) logical_end, stdout);
 118                                                 putchar('\n');
 119                                                 /* Move the remainder to the beginning of the next line.
 120                                                    The areas being copied here might overlap. */
 121                                                 memmove(line_out, line_out + logical_end, offset_out - logical_end);
 122                                                 offset_out -= logical_end;
 123                                                 for (column = i = 0; i < offset_out; i++) {
 124                                                         column = adjust_column(column, line_out[i]);
 125                                                 }
 126                                                 goto rescan;
 127                                         }
 128                                 } else {
 129                                         if (offset_out == 0) {
 130                                                 line_out[offset_out++] = c;
 131                                                 continue;
 132                                         }
 133                                 }
 134                                 line_out[offset_out++] = '\n';
 135                                 fwrite(line_out, sizeof(char), (size_t) offset_out, stdout);
 136                                 column = offset_out = 0;
 137                                 goto rescan;
 138                         }
 139
 140                         line_out[offset_out++] = c;
 141                 }
 142
 143                 if (offset_out) {
 144                         fwrite(line_out, sizeof(char), (size_t) offset_out, stdout);
 145                 }
 146
 147                 if (ferror(istream) || fclose_if_not_stdin(istream)) {
 148                         bb_perror_msg("%s", *argv);     /* Avoid multibyte problems. */
 149                         errs |= EXIT_FAILURE;
 150                 }
 151         } while (*++argv);
 152
 153         fflush_stdout_and_exit(errs);
 154 }