bool write_key_values(size_t count, const key_value* key_values)
{
bool result = true;
while (count-->0) {
result = result && write_key_value(key_values++);
}
return result;
}
static int write_key(const char *pathname, const char *key, const char *value, int icase)
{
struct stat st;
char *map, *off, *end, *str;
off_t size;
size_t base;
int fd, len, err = 0;
fd = open(pathname, O_RDWR);
if (fd < 0)
return -errno;
if (flock(fd, LOCK_EX) < 0) {
err = -errno;
goto close;
}
if (fstat(fd, &st) < 0) {
err = -errno;
goto unlock;
}
size = st.st_size;
if (!size) {
if (value) {
lseek(fd, size, SEEK_SET);
err = write_key_value(fd, key, value);
}
goto unlock;
}
map = mmap(NULL, size, PROT_READ | PROT_WRITE,
MAP_PRIVATE | MAP_LOCKED, fd, 0);
if (!map || map == MAP_FAILED) {
err = -errno;
goto unlock;
}
len = strlen(key);
off = find_key(map, size, key, len, icase);
if (!off) {
munmap(map, size);
if (value) {
lseek(fd, size, SEEK_SET);
err = write_key_value(fd, key, value);
}
goto unlock;
}
base = off - map;
end = strnpbrk(off, size, "\r\n");
if (!end) {
err = -EILSEQ;
goto unmap;
}
if (value && ((ssize_t) strlen(value) == end - off - len - 1) &&
!strncmp(off + len + 1, value, end - off - len - 1))
goto unmap;
len = strspn(end, "\r\n");
end += len;
len = size - (end - map);
if (!len) {
munmap(map, size);
if (ftruncate(fd, base) < 0) {
err = -errno;
goto unlock;
}
lseek(fd, base, SEEK_SET);
if (value)
err = write_key_value(fd, key, value);
goto unlock;
}
if (len < 0 || len > size) {
err = -EILSEQ;
goto unmap;
}
str = malloc(len);
if (!str) {
err = -errno;
goto unmap;
}
memcpy(str, end, len);
munmap(map, size);
if (ftruncate(fd, base) < 0) {
err = -errno;
free(str);
goto unlock;
}
lseek(fd, base, SEEK_SET);
if (value)
err = write_key_value(fd, key, value);
if (write(fd, str, len) < 0)
err = -errno;
free(str);
goto unlock;
unmap:
munmap(map, size);
unlock:
flock(fd, LOCK_UN);
close:
fdatasync(fd);
close(fd);
errno = -err;
return err;
}