builtin-stripspace.c

   1 #include "builtin.h"
   2 #include "cache.h"
   3
   4 /*
   5  * Returns the length of a line, without trailing spaces.
   6  *
   7  * If the line ends with newline, it will be removed too.
   8  */
   9 static size_t cleanup(char *line, size_t len)
  10 {
  11         if (len) {
  12                 if (line[len - 1] == '\n')
  13                         len--;
  14
  15                 while (len) {
  16                         unsigned char c = line[len - 1];
  17                         if (!isspace(c))
  18                                 break;
  19                         len--;
  20                 }
  21         }
  22         return len;
  23 }
  24
  25 /*
  26  * Remove empty lines from the beginning and end
  27  * and also trailing spaces from every line.
  28  *
  29  * Note that the buffer will not be NUL-terminated.
  30  *
  31  * Turn multiple consecutive empty lines between paragraphs
  32  * into just one empty line.
  33  *
  34  * If the input has only empty lines and spaces,
  35  * no output will be produced.
  36  *
  37  * If last line has a newline at the end, it will be removed.
  38  *
  39  * Enable skip_comments to skip every line starting with "#".
  40  */
  41 size_t stripspace(char *buffer, size_t length, int skip_comments)
  42 {
  43         int empties = -1;
  44         size_t i, j, len, newlen;
  45         char *eol;
  46
  47         for (i = j = 0; i < length; i += len, j += newlen) {
  48                 eol = memchr(buffer + i, '\n', length - i);
  49                 len = eol ? eol - (buffer + i) + 1 : length - i;
  50
  51                 if (skip_comments && len && buffer[i] == '#') {
  52                         newlen = 0;
  53                         continue;
  54                 }
  55                 newlen = cleanup(buffer + i, len);
  56
  57                 /* Not just an empty line? */
  58                 if (newlen) {
  59                         if (empties != -1)
  60                                 buffer[j++] = '\n';
  61                         if (empties > 0)
  62                                 buffer[j++] = '\n';
  63                         empties = 0;
  64                         memmove(buffer + j, buffer + i, newlen);
  65                         continue;
  66                 }
  67                 if (empties < 0)
  68                         continue;
  69                 empties++;
  70         }
  71
  72         return j;
  73 }
  74
  75 int cmd_stripspace(int argc, const char **argv, const char *prefix)
  76 {
  77         char *buffer;
  78         unsigned long size;
  79
  80         size = 1024;
  81         buffer = xmalloc(size);
  82         if (read_pipe(0, &buffer, &size))
  83                 die("could not read the input");
  84
  85         size = stripspace(buffer, size, 0);
  86         write_or_die(1, buffer, size);
  87         if (size)
  88                 putc('\n', stdout);
  89
  90         free(buffer);
  91         return 0;
  92 }