Andrew's git - gitweb.git/blob

   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
  14static void flush(struct sha1file *f, void *buf, unsigned int count)
  15{
  16        if (0 <= f->check_fd && count)  {
  17                unsigned char check_buffer[8192];
  18                ssize_t ret = read_in_full(f->check_fd, check_buffer, count);
  19
  20                if (ret < 0)
  21                        die_errno("%s: sha1 file read error", f->name);
  22                if (ret < count)
  23                        die("%s: sha1 file truncated", f->name);
  24                if (memcmp(buf, check_buffer, count))
  25                        die("sha1 file '%s' validation error", f->name);
  26        }
  27
  28        for (;;) {
  29                int ret = xwrite(f->fd, buf, count);
  30                if (ret > 0) {
  31                        f->total += ret;
  32                        display_throughput(f->tp, f->total);
  33                        buf = (char *) buf + ret;
  34                        count -= ret;
  35                        if (count)
  36                                continue;
  37                        return;
  38                }
  39                if (!ret)
  40                        die("sha1 file '%s' write error. Out of diskspace", f->name);
  41                die_errno("sha1 file '%s' write error", f->name);
  42        }
  43}
  44
  45void sha1flush(struct sha1file *f)
  46{
  47        unsigned offset = f->offset;
  48
  49        if (offset) {
  50                git_SHA1_Update(&f->ctx, f->buffer, offset);
  51                flush(f, f->buffer, offset);
  52                f->offset = 0;
  53        }
  54}
  55
  56int sha1close(struct sha1file *f, unsigned char *result, unsigned int flags)
  57{
  58        int fd;
  59
  60        sha1flush(f);
  61        git_SHA1_Final(f->buffer, &f->ctx);
  62        if (result)
  63                hashcpy(result, f->buffer);
  64        if (flags & (CSUM_CLOSE | CSUM_FSYNC)) {
  65                /* write checksum and close fd */
  66                flush(f, f->buffer, 20);
  67                if (flags & CSUM_FSYNC)
  68                        fsync_or_die(f->fd, f->name);
  69                if (close(f->fd))
  70                        die_errno("%s: sha1 file error on close", f->name);
  71                fd = 0;
  72        } else
  73                fd = f->fd;
  74        if (0 <= f->check_fd) {
  75                char discard;
  76                int cnt = read_in_full(f->check_fd, &discard, 1);
  77                if (cnt < 0)
  78                        die_errno("%s: error when reading the tail of sha1 file",
  79                                  f->name);
  80                if (cnt)
  81                        die("%s: sha1 file has trailing garbage", f->name);
  82                if (close(f->check_fd))
  83                        die_errno("%s: sha1 file error on close", f->name);
  84        }
  85        free(f);
  86        return fd;
  87}
  88
  89int sha1write(struct sha1file *f, void *buf, unsigned int count)
  90{
  91        while (count) {
  92                unsigned offset = f->offset;
  93                unsigned left = sizeof(f->buffer) - offset;
  94                unsigned nr = count > left ? left : count;
  95                void *data;
  96
  97                if (f->do_crc)
  98                        f->crc32 = crc32(f->crc32, buf, nr);
  99
 100                if (nr == sizeof(f->buffer)) {
 101                        /* process full buffer directly without copy */
 102                        data = buf;
 103                } else {
 104                        memcpy(f->buffer + offset, buf, nr);
 105                        data = f->buffer;
 106                }
 107
 108                count -= nr;
 109                offset += nr;
 110                buf = (char *) buf + nr;
 111                left -= nr;
 112                if (!left) {
 113                        git_SHA1_Update(&f->ctx, data, offset);
 114                        flush(f, data, offset);
 115                        offset = 0;
 116                }
 117                f->offset = offset;
 118        }
 119        return 0;
 120}
 121
 122struct sha1file *sha1fd(int fd, const char *name)
 123{
 124        return sha1fd_throughput(fd, name, NULL);
 125}
 126
 127struct sha1file *sha1fd_check(const char *name)
 128{
 129        int sink, check;
 130        struct sha1file *f;
 131
 132        sink = open("/dev/null", O_WRONLY);
 133        if (sink < 0)
 134                return NULL;
 135        check = open(name, O_RDONLY);
 136        if (check < 0) {
 137                int saved_errno = errno;
 138                close(sink);
 139                errno = saved_errno;
 140                return NULL;
 141        }
 142        f = sha1fd(sink, name);
 143        f->check_fd = check;
 144        return f;
 145}
 146
 147struct sha1file *sha1fd_throughput(int fd, const char *name, struct progress *tp)
 148{
 149        struct sha1file *f = xmalloc(sizeof(*f));
 150        f->fd = fd;
 151        f->check_fd = -1;
 152        f->offset = 0;
 153        f->total = 0;
 154        f->tp = tp;
 155        f->name = name;
 156        f->do_crc = 0;
 157        git_SHA1_Init(&f->ctx);
 158        return f;
 159}
 160
 161void crc32_begin(struct sha1file *f)
 162{
 163        f->crc32 = crc32(0, NULL, 0);
 164        f->do_crc = 1;
 165}
 166
 167uint32_t crc32_end(struct sha1file *f)
 168{
 169        f->do_crc = 0;
 170        return f->crc32;
 171}