308 lines
6.5 KiB
C
308 lines
6.5 KiB
C
/*
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* GIT - The information manager from hell
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*
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* Copyright (C) Linus Torvalds, 2005
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*
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* This handles basic git sha1 object files - packing, unpacking,
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* creation etc.
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*/
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#include <stdarg.h>
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#include "cache.h"
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const char *sha1_file_directory = NULL;
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static unsigned hexval(char c)
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{
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if (c >= '0' && c <= '9')
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return c - '0';
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if (c >= 'a' && c <= 'f')
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return c - 'a' + 10;
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if (c >= 'A' && c <= 'F')
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return c - 'A' + 10;
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return ~0;
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}
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int get_sha1_hex(const char *hex, unsigned char *sha1)
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{
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int i;
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for (i = 0; i < 20; i++) {
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unsigned int val = (hexval(hex[0]) << 4) | hexval(hex[1]);
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if (val & ~0xff)
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return -1;
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*sha1++ = val;
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hex += 2;
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}
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return 0;
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}
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char * sha1_to_hex(const unsigned char *sha1)
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{
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static char buffer[50];
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static const char hex[] = "0123456789abcdef";
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char *buf = buffer;
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int i;
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for (i = 0; i < 20; i++) {
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unsigned int val = *sha1++;
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*buf++ = hex[val >> 4];
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*buf++ = hex[val & 0xf];
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}
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return buffer;
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}
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/*
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* NOTE! This returns a statically allocated buffer, so you have to be
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* careful about using it. Do a "strdup()" if you need to save the
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* filename.
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*/
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char *sha1_file_name(const unsigned char *sha1)
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{
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int i;
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static char *name, *base;
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if (!base) {
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char *sha1_file_directory = getenv(DB_ENVIRONMENT) ? : DEFAULT_DB_ENVIRONMENT;
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int len = strlen(sha1_file_directory);
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base = malloc(len + 60);
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memcpy(base, sha1_file_directory, len);
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memset(base+len, 0, 60);
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base[len] = '/';
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base[len+3] = '/';
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name = base + len + 1;
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}
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for (i = 0; i < 20; i++) {
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static char hex[] = "0123456789abcdef";
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unsigned int val = sha1[i];
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char *pos = name + i*2 + (i > 0);
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*pos++ = hex[val >> 4];
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*pos = hex[val & 0xf];
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}
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return base;
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}
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int check_sha1_signature(unsigned char *sha1, void *map, unsigned long size, const char *type)
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{
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char header[100];
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unsigned char real_sha1[20];
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SHA_CTX c;
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SHA1_Init(&c);
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SHA1_Update(&c, header, 1+sprintf(header, "%s %lu", type, size));
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SHA1_Update(&c, map, size);
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SHA1_Final(real_sha1, &c);
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return memcmp(sha1, real_sha1, 20) ? -1 : 0;
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}
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void *map_sha1_file(const unsigned char *sha1, unsigned long *size)
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{
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char *filename = sha1_file_name(sha1);
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int fd = open(filename, O_RDONLY);
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struct stat st;
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void *map;
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if (fd < 0) {
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perror(filename);
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return NULL;
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}
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if (fstat(fd, &st) < 0) {
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close(fd);
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return NULL;
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}
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map = mmap(NULL, st.st_size, PROT_READ, MAP_PRIVATE, fd, 0);
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close(fd);
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if (-1 == (int)(long)map)
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return NULL;
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*size = st.st_size;
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return map;
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}
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void * unpack_sha1_file(void *map, unsigned long mapsize, char *type, unsigned long *size)
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{
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int ret, bytes;
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z_stream stream;
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char buffer[8192];
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char *buf;
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/* Get the data stream */
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memset(&stream, 0, sizeof(stream));
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stream.next_in = map;
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stream.avail_in = mapsize;
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stream.next_out = buffer;
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stream.avail_out = sizeof(buffer);
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inflateInit(&stream);
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ret = inflate(&stream, 0);
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if (sscanf(buffer, "%10s %lu", type, size) != 2)
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return NULL;
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bytes = strlen(buffer) + 1;
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buf = malloc(*size);
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if (!buf)
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return NULL;
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memcpy(buf, buffer + bytes, stream.total_out - bytes);
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bytes = stream.total_out - bytes;
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if (bytes < *size && ret == Z_OK) {
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stream.next_out = buf + bytes;
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stream.avail_out = *size - bytes;
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while (inflate(&stream, Z_FINISH) == Z_OK)
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/* nothing */;
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}
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inflateEnd(&stream);
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return buf;
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}
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void * read_sha1_file(const unsigned char *sha1, char *type, unsigned long *size)
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{
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unsigned long mapsize;
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void *map, *buf;
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map = map_sha1_file(sha1, &mapsize);
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if (map) {
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buf = unpack_sha1_file(map, mapsize, type, size);
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munmap(map, mapsize);
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return buf;
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}
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return NULL;
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}
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void *read_tree_with_tree_or_commit_sha1(const unsigned char *sha1,
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unsigned long *size,
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unsigned char *tree_sha1_return)
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{
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char type[20];
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void *buffer;
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unsigned long isize;
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int was_commit = 0;
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unsigned char tree_sha1[20];
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buffer = read_sha1_file(sha1, type, &isize);
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/*
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* We might have read a commit instead of a tree, in which case
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* we parse out the tree_sha1 and attempt to read from there.
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* (buffer + 5) is because the tree sha1 is always at offset 5
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* in a commit record ("tree ").
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*/
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if (buffer &&
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!strcmp(type, "commit") &&
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!get_sha1_hex(buffer + 5, tree_sha1)) {
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free(buffer);
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buffer = read_sha1_file(tree_sha1, type, &isize);
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was_commit = 1;
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}
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/*
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* Now do we have something and if so is it a tree?
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*/
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if (!buffer || strcmp(type, "tree")) {
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free(buffer);
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return NULL;
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}
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*size = isize;
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if (tree_sha1_return)
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memcpy(tree_sha1_return, was_commit ? tree_sha1 : sha1, 20);
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return buffer;
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}
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int write_sha1_file(char *buf, unsigned len, unsigned char *returnsha1)
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{
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int size;
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char *compressed;
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z_stream stream;
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unsigned char sha1[20];
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SHA_CTX c;
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char *filename;
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int fd;
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/* Sha1.. */
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SHA1_Init(&c);
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SHA1_Update(&c, buf, len);
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SHA1_Final(sha1, &c);
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if (returnsha1)
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memcpy(returnsha1, sha1, 20);
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filename = sha1_file_name(sha1);
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fd = open(filename, O_WRONLY | O_CREAT | O_EXCL, 0666);
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if (fd < 0) {
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if (errno != EEXIST)
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return -1;
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/*
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* We might do collision checking here, but we'd need to
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* uncompress the old file and check it. Later.
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*/
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return 0;
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}
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/* Set it up */
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memset(&stream, 0, sizeof(stream));
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deflateInit(&stream, Z_BEST_COMPRESSION);
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size = deflateBound(&stream, len);
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compressed = malloc(size);
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/* Compress it */
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stream.next_in = buf;
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stream.avail_in = len;
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stream.next_out = compressed;
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stream.avail_out = size;
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while (deflate(&stream, Z_FINISH) == Z_OK)
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/* nothing */;
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deflateEnd(&stream);
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size = stream.total_out;
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if (write(fd, compressed, size) != size)
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die("unable to write file");
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close(fd);
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return 0;
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}
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static inline int collision_check(char *filename, void *buf, unsigned int size)
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{
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#ifdef COLLISION_CHECK
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void *map;
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int fd = open(filename, O_RDONLY);
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struct stat st;
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int cmp;
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/* Unreadable object, or object went away? Strange. */
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if (fd < 0)
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return -1;
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if (fstat(fd, &st) < 0 || size != st.st_size)
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return -1;
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map = mmap(NULL, size, PROT_READ, MAP_PRIVATE, fd, 0);
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close(fd);
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if (map == MAP_FAILED)
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return -1;
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cmp = memcmp(buf, map, size);
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munmap(map, size);
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if (cmp)
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return -1;
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#endif
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return 0;
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}
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int write_sha1_buffer(const unsigned char *sha1, void *buf, unsigned int size)
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{
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char *filename = sha1_file_name(sha1);
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int fd;
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fd = open(filename, O_WRONLY | O_CREAT | O_EXCL, 0666);
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if (fd < 0) {
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if (errno != EEXIST)
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return -1;
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if (collision_check(filename, buf, size))
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return error("SHA1 collision detected!"
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" This is bad, bad, BAD!\a\n");
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return 0;
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}
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write(fd, buf, size);
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close(fd);
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return 0;
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}
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