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_errno("sha1 file '%s' write error", f->name);
  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_errno("%s: sha1 file error on close", f->name);
  59                 fd = 0;
  60         } else
  61                 fd = f->fd;
  62         free(f);
  63         return fd;
  64 }
  65
  66 int sha1write(struct sha1file *f, void *buf, unsigned int count)
  67 {
  68         while (count) {
  69                 unsigned offset = f->offset;
  70                 unsigned left = sizeof(f->buffer) - offset;
  71                 unsigned nr = count > left ? left : count;
  72                 void *data;
  73
  74                 if (f->do_crc)
  75                         f->crc32 = crc32(f->crc32, buf, nr);
  76
  77                 if (nr == sizeof(f->buffer)) {
  78                         /* process full buffer directly without copy */
  79                         data = buf;
  80                 } else {
  81                         memcpy(f->buffer + offset, buf, nr);
  82                         data = f->buffer;
  83                 }
  84
  85                 count -= nr;
  86                 offset += nr;
  87                 buf = (char *) buf + nr;
  88                 left -= nr;
  89                 if (!left) {
  90                         git_SHA1_Update(&f->ctx, data, offset);
  91                         flush(f, data, offset);
  92                         offset = 0;
  93                 }
  94                 f->offset = offset;
  95         }
  96         return 0;
  97 }
  98
  99 struct sha1file *sha1fd(int fd, const char *name)
 100 {
 101         return sha1fd_throughput(fd, name, NULL);
 102 }
 103
 104 struct sha1file *sha1fd_throughput(int fd, const char *name, struct progress *tp)
 105 {
 106         struct sha1file *f = xmalloc(sizeof(*f));
 107         f->fd = fd;
 108         f->offset = 0;
 109         f->total = 0;
 110         f->tp = tp;
 111         f->name = name;
 112         f->do_crc = 0;
 113         git_SHA1_Init(&f->ctx);
 114         return f;
 115 }
 116
 117 void crc32_begin(struct sha1file *f)
 118 {
 119         f->crc32 = crc32(0, Z_NULL, 0);
 120         f->do_crc = 1;
 121 }
 122
 123 uint32_t crc32_end(struct sha1file *f)
 124 {
 125         f->do_crc = 0;
 126         return f->crc32;
 127 }