Commit b505e4eb authored by Mark Adler's avatar Mark Adler

Add --synchronous option to push written data to permanent storage.

This adds an option present in gzip to improve interoperability.
parent fc10bb00
......@@ -333,9 +333,9 @@
#include <sys/time.h> // utimes(), gettimeofday(), struct timeval
#include <unistd.h> // unlink(), _exit(), read(), write(), close(),
// lseek(), isatty(), chown()
// lseek(), isatty(), chown(), fsync()
#include <fcntl.h> // open(), O_CREAT, O_EXCL, O_RDONLY, O_TRUNC,
#include <dirent.h> // opendir(), readdir(), closedir(), DIR,
// struct dirent
#include <limits.h> // UINT_MAX, INT_MAX
......@@ -499,6 +499,7 @@ local struct {
int pipeout; // write output to stdout even if file
int keep; // true to prevent deletion of input file
int force; // true to overwrite, compress links, cat
int sync; // true to flush output file
int form; // gzip = 0, zlib = 1, zip = 2 or 3
unsigned char magic1; // first byte of possible header when decoding
int recurse; // true to dive down into directory structure
......@@ -3610,6 +3611,29 @@ local void touch(char *path, time_t t) {
(void)utimes(path, times);
// Request that all data buffered by the operating system for g.outd be written
// to the permanent storage device. If fsync(fd) is used (POSIX), then all of
// the data is sent to the device, but will likely be buffered in volatile
// memory on the device itself, leaving open a window of vulnerability.
// fcntl(fd, F_FULLSYNC) on the other hand, available in macOS only, will
// request and wait for the device to write out its buffered data to permanent
// storage.
// For a future Windows port of pigz, winbase.h should be included and
// FlushFileBuffers() used, which also waits for the device write out its
// buffered data to permanent storage.
local void out_push(void) {
if (g.outd == -1)
int ret = fcntl(g.outd, F_FULLSYNC);
int ret = fsync(g.outd);
if (ret == -1)
throw(errno, "sync error on %s (%s)", g.outf, strerror(errno));
// Process provided input file, or stdin if path is NULL. process() can call
// itself for recursive directory processing.
local void process(char *path) {
......@@ -3903,6 +3927,8 @@ local void process(char *path) {
// finish up, copy attributes, set times, delete original
if (g.outd != -1 && g.outd != 1) {
if (g.sync)
out_push(); // push to permanent storage
if (close(g.outd))
throw(errno, "write error on %s (%s)", g.outf, strerror(errno));
g.outd = -1; // now prevent deletion on interrupt
......@@ -3973,6 +3999,7 @@ local char *helptext[] = {
" -v, --verbose Provide more verbose output",
" -V --version Show the version of pigz",
" -Y --synchronous Force output file write to permanent storage",
" -z, --zlib Compress to zlib (.zz) instead of gzip format",
" -- All arguments after \"--\" are treated as files"
......@@ -4042,6 +4069,7 @@ local void defaults(void) {
g.list = 0; // compress
g.keep = 0; // delete input file once compressed
g.force = 0; // don't overwrite, don't compress links
g.sync = 0; // don't force a flush on output
g.recurse = 0; // don't go into directories
g.form = 0; // use gzip format
......@@ -4056,9 +4084,9 @@ local char *longopts[][2] = {
{"help", "h"}, {"independent", "i"}, {"keep", "k"}, {"license", "L"},
{"list", "l"}, {"name", "N"}, {"no-name", "n"}, {"no-time", "m"},
{"processes", "p"}, {"quiet", "q"}, {"recursive", "r"}, {"rsyncable", "R"},
{"silent", "q"}, {"stdout", "c"}, {"suffix", "S"}, {"test", "t"},
{"time", "M"}, {"to-stdout", "c"}, {"uncompress", "d"}, {"verbose", "v"},
{"version", "V"}, {"zip", "K"}, {"zlib", "z"}};
{"silent", "q"}, {"stdout", "c"}, {"suffix", "S"}, {"synchronous", "Y"},
{"test", "t"}, {"time", "M"}, {"to-stdout", "c"}, {"uncompress", "d"},
{"verbose", "v"}, {"version", "V"}, {"zip", "K"}, {"zlib", "z"}};
#define NLOPTS (sizeof(longopts) / (sizeof(char *) << 1))
// Either new buffer size, new compression level, or new number of processes.
......@@ -4171,6 +4199,7 @@ local int option(char *arg) {
if (g.verbosity > 1)
fprintf(stderr, "zlib %s\n", zlibVersion());
case 'Y': g.sync = 1; break;
case 'Z':
throw(EINVAL, "invalid option: LZW output not supported: %s",
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