csum-file.c

   1 /*
   2  * csum-file.c
   3  *
   4  * Copyright (C) 2005 Linus Torvalds
   5  *
   6  * Simple file write infrastructure for writing SHA1-summed
   7  * files. Useful when you write a file that you want to be
   8  * able to verify hasn't been messed with afterwards.
   9  */
  10 #include "cache.h"
  11 #include "progress.h"
  12 #include "csum-file.h"
  13
  14 static void sha1flush(struct sha1file *f, void *buf, unsigned int count)
  15 {
  16         for (;;) {
  17                 int ret = xwrite(f->fd, buf, count);
  18                 if (ret > 0) {
  19                         f->total += ret;
  20                         display_throughput(f->tp, f->total);
  21                         buf = (char *) buf + ret;
  22                         count -= ret;
  23                         if (count)
  24                                 continue;
  25                         return;
  26                 }
  27                 if (!ret)
  28                         die("sha1 file '%s' write error. Out of diskspace", f->name);
  29                 die("sha1 file '%s' write error (%s)", f->name, strerror(errno));
  30         }
  31 }
  32
  33 int sha1close(struct sha1file *f, unsigned char *result, unsigned int flags)
  34 {
  35         int fd;
  36         unsigned offset = f->offset;
  37
  38         if (offset) {
  39                 git_SHA1_Update(&f->ctx, f->buffer, offset);
  40                 sha1flush(f, f->buffer, offset);
  41                 f->offset = 0;
  42         }
  43         git_SHA1_Final(f->buffer, &f->ctx);
  44         if (result)
  45                 hashcpy(result, f->buffer);
  46         if (flags & (CSUM_CLOSE | CSUM_FSYNC)) {
  47                 /* write checksum and close fd */
  48                 sha1flush(f, f->buffer, 20);
  49                 if (flags & CSUM_FSYNC)
  50                         fsync_or_die(f->fd, f->name);
  51                 if (close(f->fd))
  52                         die("%s: sha1 file error on close (%s)",
  53                             f->name, strerror(errno));
  54                 fd = 0;
  55         } else
  56                 fd = f->fd;
  57         free(f);
  58         return fd;
  59 }
  60
  61 int sha1write(struct sha1file *f, void *buf, unsigned int count)
  62 {
  63         while (count) {
  64                 unsigned offset = f->offset;
  65                 unsigned left = sizeof(f->buffer) - offset;
  66                 unsigned nr = count > left ? left : count;
  67                 void *data;
  68
  69                 if (f->do_crc)
  70                         f->crc32 = crc32(f->crc32, buf, nr);
  71
  72                 if (nr == sizeof(f->buffer)) {
  73                         /* process full buffer directly without copy */
  74                         data = buf;
  75                 } else {
  76                         memcpy(f->buffer + offset, buf, nr);
  77                         data = f->buffer;
  78                 }
  79
  80                 count -= nr;
  81                 offset += nr;
  82                 buf = (char *) buf + nr;
  83                 left -= nr;
  84                 if (!left) {
  85                         git_SHA1_Update(&f->ctx, data, offset);
  86                         sha1flush(f, data, offset);
  87                         offset = 0;
  88                 }
  89                 f->offset = offset;
  90         }
  91         return 0;
  92 }
  93
  94 struct sha1file *sha1fd(int fd, const char *name)
  95 {
  96         return sha1fd_throughput(fd, name, NULL);
  97 }
  98
  99 struct sha1file *sha1fd_throughput(int fd, const char *name, struct progress *tp)
 100 {
 101         struct sha1file *f = xmalloc(sizeof(*f));
 102         f->fd = fd;
 103         f->offset = 0;
 104         f->total = 0;
 105         f->tp = tp;
 106         f->name = name;
 107         f->do_crc = 0;
 108         git_SHA1_Init(&f->ctx);
 109         return f;
 110 }
 111
 112 void crc32_begin(struct sha1file *f)
 113 {
 114         f->crc32 = crc32(0, Z_NULL, 0);
 115         f->do_crc = 1;
 116 }
 117
 118 uint32_t crc32_end(struct sha1file *f)
 119 {
 120         f->do_crc = 0;
 121         return f->crc32;
 122 }