How to use libarchive properly? - c++

Question

I'm trying to zip/unzip folders using libarchive. But, I couldn't know how to use it?

Answer 1

Include these:
#include <archive.h>
#include <archive_entry.h>
And compile with:
gcc -Wall -o test test.c -lz -lbz2 -larchive
So all together it should look something like this
#include <sys/types.h>
#include <sys/stat.h>
#include <archive.h>
#include <archive_entry.h>
#include <fcntl.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
static int
copy_data(struct archive *ar, struct archive *aw)
{
int r;
const void *buff;
size_t size;
off_t offset;
for (;;) {
r = archive_read_data_block(ar, &buff, &size, &offset);
if (r == ARCHIVE_EOF)
return (ARCHIVE_OK);
if (r < ARCHIVE_OK)
return (r);
r = archive_write_data_block(aw, buff, size, offset);
if (r < ARCHIVE_OK) {
fprintf(stderr, "%s\n", archive_error_string(aw));
return (r);
}
}
}
static int
extract(const char *filename)
{
struct archive *a;
struct archive *ext;
struct archive_entry *entry;
int flags;
int r;
/* Select which attributes we want to restore. */
flags = ARCHIVE_EXTRACT_TIME;
flags |= ARCHIVE_EXTRACT_PERM;
flags |= ARCHIVE_EXTRACT_ACL;
flags |= ARCHIVE_EXTRACT_FFLAGS;
a = archive_read_new();
archive_read_support_format_all(a);
ext = archive_write_disk_new();
archive_write_disk_set_options(ext, flags);
archive_write_disk_set_standard_lookup(ext);
if ((r = archive_read_open_filename(a, filename, 10240)))
return 1;
for (;;) {
r = archive_read_next_header(a, &entry);
if (r == ARCHIVE_EOF)
break;
if (r < ARCHIVE_OK)
fprintf(stderr, "%s\n", archive_error_string(a));
if (r < ARCHIVE_WARN)
return 1;
r = archive_write_header(ext, entry);
if (r < ARCHIVE_OK)
fprintf(stderr, "%s\n", archive_error_string(ext));
else if (archive_entry_size(entry) > 0) {
r = copy_data(a, ext);
if (r < ARCHIVE_OK)
fprintf(stderr, "%s\n", archive_error_string(ext));
if (r < ARCHIVE_WARN)
return 1;
}
r = archive_write_finish_entry(ext);
if (r < ARCHIVE_OK)
fprintf(stderr, "%s\n", archive_error_string(ext));
if (r < ARCHIVE_WARN)
return 1;
}
archive_read_close(a);
archive_read_free(a);
archive_write_close(ext);
archive_write_free(ext);
return 0;
}
int main ( int argc, const char **argv )
{
return extract (argv[1]);;
}

Answer 2

Perhaps this link will help? Examples from LibArchive Wiki
For example, here is the code they give to write files to an archive:
void
write_archive(const char *outname, const char **filename)
{
struct archive *a;
struct archive_entry *entry;
struct stat st;
char buff[8192];
int len;
int fd;
a = archive_write_new();
archive_write_add_filter_gzip(a);
archive_write_set_format_pax_restricted(a); // Note 1
archive_write_open_filename(a, outname, 10240);
while (*filename) {
stat(*filename, &st);
entry = archive_entry_new(); // Note 2
archive_entry_set_pathname(entry, *filename);
archive_entry_set_size(entry, st.st_size); // Note 3
archive_entry_set_filetype(entry, AE_IFREG);
archive_entry_set_perm(entry, 0644);
archive_write_header(a, entry);
fd = open(*filename, O_RDONLY);
len = read(fd, buff, sizeof(buff));
while ( len > 0 ) {
archive_write_data(a, buff, len);
len = read(fd, buff, sizeof(buff));
}
close(fd);
archive_entry_free(entry);
filename++;
}
archive_write_close(a); // Note 4
archive_write_free(a); // Note 5
}
int main(int argc, const char **argv)
{
const char *outname;
argv++;
outname = argv++;
write_archive(outname, argv);
return 0;
}