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 flush(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 void sha1flush(struct sha1file *f)
  34 {
  35         unsigned offset = f->offset;
  36
  37         if (offset) {
  38                 git_SHA1_Update(&f->ctx, f->buffer, offset);
  39                 flush(f, f->buffer, offset);
  40                 f->offset = 0;
  41         }
  42 }
  43
  44 int sha1close(struct sha1file *f, unsigned char *result, unsigned int flags)
  45 {
  46         int fd;
  47
  48         sha1flush(f);
  49         git_SHA1_Final(f->buffer, &f->ctx);
  50         if (result)
  51                 hashcpy(result, f->buffer);
  52         if (flags & (CSUM_CLOSE | CSUM_FSYNC)) {
  53                 /* write checksum and close fd */
  54                 flush(f, f->buffer, 20);
  55                 if (flags & CSUM_FSYNC)
  56                         fsync_or_die(f->fd, f->name);
  57                 if (close(f->fd))
  58                         die("%s: sha1 file error on close (%s)",
  59                             f->name, strerror(errno));
  60                 fd = 0;
  61         } else
  62                 fd = f->fd;
  63         free(f);
  64         return fd;
  65 }
  66
  67 int sha1write(struct sha1file *f, void *buf, unsigned int count)
  68 {
  69         while (count) {
  70                 unsigned offset = f->offset;
  71                 unsigned left = sizeof(f->buffer) - offset;
  72                 unsigned nr = count > left ? left : count;
  73                 void *data;
  74
  75                 if (f->do_crc)
  76                         f->crc32 = crc32(f->crc32, buf, nr);
  77
  78                 if (nr == sizeof(f->buffer)) {
  79                         /* process full buffer directly without copy */
  80                         data = buf;
  81                 } else {
  82                         memcpy(f->buffer + offset, buf, nr);
  83                         data = f->buffer;
  84                 }
  85
  86                 count -= nr;
  87                 offset += nr;
  88                 buf = (char *) buf + nr;
  89                 left -= nr;
  90                 if (!left) {
  91                         git_SHA1_Update(&f->ctx, data, offset);
  92                         flush(f, data, offset);
  93                         offset = 0;
  94                 }
  95                 f->offset = offset;
  96         }
  97         return 0;
  98 }
  99
 100 struct sha1file *sha1fd(int fd, const char *name)
 101 {
 102         return sha1fd_throughput(fd, name, NULL);
 103 }
 104
 105 struct sha1file *sha1fd_throughput(int fd, const char *name, struct progress *tp)
 106 {
 107         struct sha1file *f = xmalloc(sizeof(*f));
 108         f->fd = fd;
 109         f->offset = 0;
 110         f->total = 0;
 111         f->tp = tp;
 112         f->name = name;
 113         f->do_crc = 0;
 114         git_SHA1_Init(&f->ctx);
 115         return f;
 116 }
 117
 118 void crc32_begin(struct sha1file *f)
 119 {
 120         f->crc32 = crc32(0, Z_NULL, 0);
 121         f->do_crc = 1;
 122 }
 123
 124 uint32_t crc32_end(struct sha1file *f)
 125 {
 126         f->do_crc = 0;
 127         return f->crc32;
 128 }