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Merge "Vastly reduce the number of read(2)s done in tzload."

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Elliott Hughes 2014-02-28 16:23:40 +00:00 committed by Gerrit Code Review
commit e9db4a976f
1 changed files with 23 additions and 9 deletions
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36
libc/tzcode/localtime.c
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@ -2167,26 +2167,40 @@ static int __bionic_open_tzdata_path(const char* path_prefix_variable, const cha
}
off_t specific_zone_offset = -1;
static const size_t NAME_LENGTH = 40;
unsigned char buf[NAME_LENGTH + 3 * sizeof(int32_t)];
size_t id_count = (ntohl(header.data_offset) - ntohl(header.index_offset)) / sizeof(buf);
for (size_t i = 0; i < id_count; ++i) {
if (TEMP_FAILURE_RETRY(read(fd, buf, sizeof(buf))) != (ssize_t) sizeof(buf)) {
break;
ssize_t index_size = ntohl(header.data_offset) - ntohl(header.index_offset);
char* index = malloc(index_size);
if (TEMP_FAILURE_RETRY(read(fd, index, index_size)) != index_size) {
fprintf(stderr, "%s: could not read index of \"%s\": %s\n",
__FUNCTION__, path, (bytes_read == -1) ? strerror(errno) : "short read");
free(index);
close(fd);
return -1;
}
static const size_t NAME_LENGTH = 40;
struct index_entry_t {
char buf[NAME_LENGTH];
int32_t start;
int32_t length;
int32_t raw_gmt_offset;
};
size_t id_count = (ntohl(header.data_offset) - ntohl(header.index_offset)) / sizeof(struct index_entry_t);
struct index_entry_t* entry = (struct index_entry_t*) index;
for (size_t i = 0; i < id_count; ++i) {
char this_id[NAME_LENGTH + 1];
memcpy(this_id, buf, NAME_LENGTH);
memcpy(this_id, entry->buf, NAME_LENGTH);
this_id[NAME_LENGTH] = '\0';
if (strcmp(this_id, olson_id) == 0) {
specific_zone_offset = to_int(buf + NAME_LENGTH) + ntohl(header.data_offset);
*data_size = to_int(buf + NAME_LENGTH + sizeof(int32_t));
specific_zone_offset = ntohl(entry->start) + ntohl(header.data_offset);
*data_size = ntohl(entry->length);
break;
}
++entry;
}
free(index);
if (specific_zone_offset == -1) {
XLOG(("%s: couldn't find zone \"%s\"\n", __FUNCTION__, olson_id));