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/* Copyright © 2014 Brandon L Black <blblack@gmail.com>
*
* This file is part of gdnsd.
*
* gdnsd is free software: you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation, either version 3 of the License, or
* (at your option) any later version.
*
* gdnsd is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with gdnsd. If not, see <http://www.gnu.org/licenses/>.
*
*/
#include <config.h>
#include <gdnsd/file.h>
#include <gdnsd/compiler.h>
#include <gdnsd/alloc.h>
#include <gdnsd/log.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <sys/mman.h>
#include <string.h>
#include <unistd.h>
#include <stdlib.h>
#include <fcntl.h>
// Avoid mmap for smaller files (<1MB)
#define SIZE_CUTOFF_MMAP 1048576U
struct gdnsd_fmap_s_ {
void* buf;
size_t len;
bool is_mapped;
};
gdnsd_fmap_t* gdnsd_fmap_new(const char* fn, const bool seq, const bool mod)
{
const int fd = open(fn, O_RDONLY | O_CLOEXEC);
if (fd < 0) {
log_err("Cannot open '%s' for reading: %s", fn, logf_errno());
return NULL;
}
struct stat st;
if (fstat(fd, &st) < 0) {
log_err("Cannot fstat '%s': %s", fn, logf_errno());
close(fd);
return NULL;
}
// S_ISREG won't fail on symlink here, because this is fstat()
// and the earlier open() didn't use O_NOFOLLOW.
if (!S_ISREG(st.st_mode) || st.st_size < 0) {
log_err("'%s' is not a regular file", fn);
close(fd);
return NULL;
}
const size_t len = (size_t)st.st_size;
char* mapbuf = NULL;
bool is_mapped = false;
if (len >= SIZE_CUTOFF_MMAP) {
const int prot = mod ? (PROT_READ | PROT_WRITE) : PROT_READ;
const int flags = mod ? MAP_PRIVATE : MAP_SHARED;
mapbuf = mmap(NULL, len, prot, flags, fd, 0);
if (mapbuf == MAP_FAILED) {
log_err("Cannot mmap '%s': %s", fn, logf_errno());
close(fd);
return NULL;
}
int advice = POSIX_MADV_WILLNEED;
if (seq)
advice |= POSIX_MADV_SEQUENTIAL;
else
advice |= POSIX_MADV_RANDOM;
(void)posix_madvise(mapbuf, len, advice);
is_mapped = true;
} else if (len) {
mapbuf = xmalloc(len);
size_t have_slurped = 0;
do {
ssize_t readrv = read(fd, mapbuf + have_slurped, len - have_slurped);
if (unlikely(readrv < 0)) {
if (errno == EINTR)
continue;
log_err("read of '%s' failed: %s", fn, logf_errno());
free(mapbuf);
close(fd);
return NULL;
}
have_slurped += (size_t)readrv;
} while (have_slurped < len);
} else {
// we don't want callers to have to care about cases where this call
// was successful but the buffer pointer is NULL due to len == 0, so
// allocate a 1-byte buffer containing a NUL for these cases.
mapbuf = xcalloc(1);
}
if (close(fd))
log_err("Cannot close '%s', continuing anyways: %s", fn, logf_errno());
gdnsd_fmap_t* fmap = xmalloc(sizeof(*fmap));
fmap->buf = mapbuf;
fmap->len = len;
fmap->is_mapped = is_mapped;
return fmap;
}
void* gdnsd_fmap_get_buf(const gdnsd_fmap_t* fmap)
{
gdnsd_assert(fmap->buf);
return fmap->buf;
}
size_t gdnsd_fmap_get_len(const gdnsd_fmap_t* fmap)
{
gdnsd_assert(fmap->buf);
return fmap->len;
}
bool gdnsd_fmap_delete(gdnsd_fmap_t* fmap)
{
gdnsd_assert(fmap->buf);
bool rv = false; // true == error
if (fmap->is_mapped) {
if (munmap(fmap->buf, fmap->len)) {
log_err("Cannot munmap() %p: %s", fmap->buf, logf_errno());
rv = true;
}
} else {
free(fmap->buf);
}
free(fmap);
return rv;
}
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