write_or_die.c

   1 #include "cache.h"
   2
   3 /*
   4  * Some cases use stdio, but want to flush after the write
   5  * to get error handling (and to get better interactive
   6  * behaviour - not buffering excessively).
   7  *
   8  * Of course, if the flush happened within the write itself,
   9  * we've already lost the error code, and cannot report it any
  10  * more. So we just ignore that case instead (and hope we get
  11  * the right error code on the flush).
  12  *
  13  * If the file handle is stdout, and stdout is a file, then skip the
  14  * flush entirely since it's not needed.
  15  */
  16 void maybe_flush_or_die(FILE *f, const char *desc)
  17 {
  18         static int skip_stdout_flush = -1;
  19         struct stat st;
  20         char *cp;
  21
  22         if (f == stdout) {
  23                 if (skip_stdout_flush < 0) {
  24                         cp = getenv("GIT_FLUSH");
  25                         if (cp)
  26                                 skip_stdout_flush = (atoi(cp) == 0);
  27                         else if ((fstat(fileno(stdout), &st) == 0) &&
  28                                  S_ISREG(st.st_mode))
  29                                 skip_stdout_flush = 1;
  30                         else
  31                                 skip_stdout_flush = 0;
  32                 }
  33                 if (skip_stdout_flush && !ferror(f))
  34                         return;
  35         }
  36         if (fflush(f)) {
  37                 /*
  38                  * On Windows, EPIPE is returned only by the first write()
  39                  * after the reading end has closed its handle; subsequent
  40                  * write()s return EINVAL.
  41                  */
  42                 if (errno == EPIPE || errno == EINVAL)
  43                         exit(0);
  44                 die("write failure on %s: %s", desc, strerror(errno));
  45         }
  46 }
  47
  48 ssize_t read_in_full(int fd, void *buf, size_t count)
  49 {
  50         char *p = buf;
  51         ssize_t total = 0;
  52
  53         while (count > 0) {
  54                 ssize_t loaded = xread(fd, p, count);
  55                 if (loaded <= 0)
  56                         return total ? total : loaded;
  57                 count -= loaded;
  58                 p += loaded;
  59                 total += loaded;
  60         }
  61
  62         return total;
  63 }
  64
  65 ssize_t write_in_full(int fd, const void *buf, size_t count)
  66 {
  67         const char *p = buf;
  68         ssize_t total = 0;
  69
  70         while (count > 0) {
  71                 ssize_t written = xwrite(fd, p, count);
  72                 if (written < 0)
  73                         return -1;
  74                 if (!written) {
  75                         errno = ENOSPC;
  76                         return -1;
  77                 }
  78                 count -= written;
  79                 p += written;
  80                 total += written;
  81         }
  82
  83         return total;
  84 }
  85
  86 void write_or_die(int fd, const void *buf, size_t count)
  87 {
  88         if (write_in_full(fd, buf, count) < 0) {
  89                 if (errno == EPIPE)
  90                         exit(0);
  91                 die("write error (%s)", strerror(errno));
  92         }
  93 }
  94
  95 int write_or_whine_pipe(int fd, const void *buf, size_t count, const char *msg)
  96 {
  97         if (write_in_full(fd, buf, count) < 0) {
  98                 if (errno == EPIPE)
  99                         exit(0);
 100                 fprintf(stderr, "%s: write error (%s)\n",
 101                         msg, strerror(errno));
 102                 return 0;
 103         }
 104
 105         return 1;
 106 }
 107
 108 int write_or_whine(int fd, const void *buf, size_t count, const char *msg)
 109 {
 110         if (write_in_full(fd, buf, count) < 0) {
 111                 fprintf(stderr, "%s: write error (%s)\n",
 112                         msg, strerror(errno));
 113                 return 0;
 114         }
 115
 116         return 1;
 117 }