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, unsigned int count)
  15 {
  16         void *buf = f->buffer;
  17
  18         for (;;) {
  19                 int ret = xwrite(f->fd, buf, count);
  20                 if (ret > 0) {
  21                         f->total += ret;
  22                         display_throughput(f->tp, f->total);
  23                         buf = (char *) buf + ret;
  24                         count -= ret;
  25                         if (count)
  26                                 continue;
  27                         return;
  28                 }
  29                 if (!ret)
  30                         die("sha1 file '%s' write error. Out of diskspace", f->name);
  31                 die("sha1 file '%s' write error (%s)", f->name, strerror(errno));
  32         }
  33 }
  34
  35 void sha1flush(struct sha1file *f)
  36 {
  37         unsigned offset = f->offset;
  38
  39         if (offset) {
  40                 SHA1_Update(&f->ctx, f->buffer, offset);
  41                 flush(f, offset);
  42                 f->offset = 0;
  43         }
  44 }
  45
  46 int sha1close(struct sha1file *f, unsigned char *result, unsigned int flags)
  47 {
  48         int fd;
  49
  50         sha1flush(f);
  51         SHA1_Final(f->buffer, &f->ctx);
  52         if (result)
  53                 hashcpy(result, f->buffer);
  54         if (flags & (CSUM_CLOSE | CSUM_FSYNC)) {
  55                 /* write checksum and close fd */
  56                 flush(f, 20);
  57                 if (flags & CSUM_FSYNC)
  58                         fsync_or_die(f->fd, f->name);
  59                 if (close(f->fd))
  60                         die("%s: sha1 file error on close (%s)",
  61                             f->name, strerror(errno));
  62                 fd = 0;
  63         } else
  64                 fd = f->fd;
  65         free(f);
  66         return fd;
  67 }
  68
  69 int sha1write(struct sha1file *f, void *buf, unsigned int count)
  70 {
  71         if (f->do_crc)
  72                 f->crc32 = crc32(f->crc32, buf, count);
  73         while (count) {
  74                 unsigned offset = f->offset;
  75                 unsigned left = sizeof(f->buffer) - offset;
  76                 unsigned nr = count > left ? left : count;
  77
  78                 memcpy(f->buffer + offset, buf, nr);
  79                 count -= nr;
  80                 offset += nr;
  81                 buf = (char *) buf + nr;
  82                 left -= nr;
  83                 if (!left) {
  84                         SHA1_Update(&f->ctx, f->buffer, offset);
  85                         flush(f, offset);
  86                         offset = 0;
  87                 }
  88                 f->offset = offset;
  89         }
  90         return 0;
  91 }
  92
  93 struct sha1file *sha1fd(int fd, const char *name)
  94 {
  95         return sha1fd_throughput(fd, name, NULL);
  96 }
  97
  98 struct sha1file *sha1fd_throughput(int fd, const char *name, struct progress *tp)
  99 {
 100         struct sha1file *f = xmalloc(sizeof(*f));
 101         f->fd = fd;
 102         f->offset = 0;
 103         f->total = 0;
 104         f->tp = tp;
 105         f->name = name;
 106         f->do_crc = 0;
 107         SHA1_Init(&f->ctx);
 108         return f;
 109 }
 110
 111 void crc32_begin(struct sha1file *f)
 112 {
 113         f->crc32 = crc32(0, Z_NULL, 0);
 114         f->do_crc = 1;
 115 }
 116
 117 uint32_t crc32_end(struct sha1file *f)
 118 {
 119         f->do_crc = 0;
 120         return f->crc32;
 121 }