Commit Diff
Diff:
/dev/null
5391aec51faf860600b91bc2a3e253d119896de1
Commit:
5391aec51faf860600b91bc2a3e253d119896de1
Tree:
6a417e0a892c4f7c8bf34a780a80c289c6d16f6e
Author:
Omar Polo <op@omarpolo.com>
Date:
Sat Aug 21 15:27:52 2021 UTC
Message:
initial commit
commit - /dev/null
commit + 5391aec51faf860600b91bc2a3e253d119896de1
blob - /dev/null
blob + 0a58a0c2a8130893bf70250fd1b46bff2b4b37a1 (mode 644)
--- /dev/null
+++ README.md
@@ -0,0 +1,32 @@
+# zip utils
+
+This is the code for the series of posts about zip files in my blog.
+
+To compile the first program:
+
+ cc zipls.c -o zipls
+
+To compile the second program:
+
+ cc zipview.c -o zipview -lz
+
+
+## License
+
+This is free and unencumbered software released into the public
+domain; see the UNLICENSE file.
+
+
+## Posts
+
+Posts (english):
+
+ - [Inspecting zip
+ files](https://www.omarpolo.com/post/inspecting-zips.html)
+ - [Extracting files from
+ zips](https://www.omarpolo.com/post/extracting-from-zips.html)
+
+Posts (italian and only over gemini):
+
+ - [Elencare i file di uno
+ zip](gemini://it.omarpolo.com/articoli/elencare-i-file-di-uno-zip.gmi)
blob - /dev/null
blob + 68a49daad8ff7e35068f2b7a97d643aab440eaec (mode 644)
--- /dev/null
+++ UNLICENSE
@@ -0,0 +1,24 @@
+This is free and unencumbered software released into the public domain.
+
+Anyone is free to copy, modify, publish, use, compile, sell, or
+distribute this software, either in source code form or as a compiled
+binary, for any purpose, commercial or non-commercial, and by any
+means.
+
+In jurisdictions that recognize copyright laws, the author or authors
+of this software dedicate any and all copyright interest in the
+software to the public domain. We make this dedication for the benefit
+of the public at large and to the detriment of our heirs and
+successors. We intend this dedication to be an overt act of
+relinquishment in perpetuity of all present and future rights to this
+software under copyright law.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
+EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
+MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
+IN NO EVENT SHALL THE AUTHORS BE LIABLE FOR ANY CLAIM, DAMAGES OR
+OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE,
+ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
+OTHER DEALINGS IN THE SOFTWARE.
+
+For more information, please refer to <http://unlicense.org/>
blob - /dev/null
blob + 460636c9864cbd26ebdce1e738325a8d95f1720e (mode 644)
--- /dev/null
+++ zipls.c
@@ -0,0 +1,133 @@
+/*
+ * This is free and unencumbered software released into the public domain.
+ */
+
+#include <sys/mman.h>
+
+#include <endian.h>
+#include <err.h>
+#include <fcntl.h>
+#include <limits.h>
+#include <stdint.h>
+#include <stdio.h>
+#include <string.h>
+#include <unistd.h>
+#include <zlib.h>
+
+#define MIN(a, b) ((a) < (b) ? (a) : (b))
+
+void *
+find_central_directory(uint8_t *addr, size_t len)
+{
+ uint32_t offset;
+ uint16_t clen;
+ uint8_t *p, *end;
+
+ /*
+ * At -22 bytes from the end there is the end of the central
+ * directory assuming an empty comment. It's a sensible place
+ * from which start.
+ */
+ if (len < 22)
+ return NULL;
+ end = addr + len;
+ p = end - 22;
+
+again:
+ for (; p > addr; --p)
+ if (memcmp(p, "\x50\x4b\x05\x06", 4) == 0)
+ break;
+
+ if (p == addr)
+ return NULL;
+
+ /* read comment length */
+ memcpy(&clen, p + 20, sizeof(clen));
+ clen = le16toh(clen);
+
+ /* false signature inside a comment? */
+ if (clen + 22 != end - p) {
+ p--;
+ goto again;
+ }
+
+ /* read the offset for the central directory */
+ memcpy(&offset, p + 16, sizeof(offset));
+ offset = le32toh(offset);
+
+ if (addr + offset > p)
+ return NULL;
+
+ return addr + offset;
+}
+
+void
+ls(uint8_t *zip, size_t len, uint8_t *cd)
+{
+ uint16_t flen, xlen, clen;
+ uint8_t *end;
+ char filename[PATH_MAX];
+
+ end = zip + len;
+ while (cd < end - 46 && memcmp(cd, "\x50\x4b\x01\x02", 4) == 0) {
+ memcpy(&flen, cd + 28, sizeof(flen));
+ memcpy(&xlen, cd + 28 + 2, sizeof(xlen));
+ memcpy(&clen, cd + 28 + 2 + 2, sizeof(clen));
+
+ flen = le16toh(flen);
+ xlen = le16toh(xlen);
+ clen = le16toh(clen);
+
+ memset(filename, 0, sizeof(filename));
+ memcpy(filename, cd + 46, MIN(sizeof(filename)-1, flen));
+
+ printf("%s\n", filename);
+
+ cd += 46 + flen + xlen + clen;
+ }
+}
+
+void *
+map_file(int fd, size_t *len)
+{
+ off_t jump;
+ void *addr;
+
+ if ((jump = lseek(fd, 0, SEEK_END)) == -1)
+ err(1, "lseek");
+
+ if (lseek(fd, 0, SEEK_SET) == -1)
+ err(1, "lseek");
+
+ if ((addr = mmap(NULL, jump, PROT_READ, MAP_PRIVATE, fd, 0))
+ == MAP_FAILED)
+ err(1, "mmap");
+
+ *len = jump;
+ return addr;
+}
+
+int
+main(int argc, char **argv)
+{
+ int fd;
+ void *zip, *cd;
+ size_t len;
+
+ if (argc != 2)
+ errx(1, "missing file to inspect");
+
+ if ((fd = open(argv[1], O_RDONLY)) == -1)
+ err(1, "can't open %s", argv[1]);
+
+ zip = map_file(fd, &len);
+ if ((cd = find_central_directory(zip, len)) == NULL)
+ errx(1, "can't find the central directory");
+
+ ls(zip, len, cd);
+
+ munmap(zip, len);
+ close(fd);
+
+ return 0;
+}
blob - /dev/null
blob + 74a7ae855184cc21722d0a385df995f4da76ab7b (mode 644)
--- /dev/null
+++ zipview.c
@@ -0,0 +1,305 @@
+/*
+ * This is free and unencumbered software released into the public domain.
+ */
+
+#include <sys/mman.h>
+
+#include <endian.h>
+#include <err.h>
+#include <fcntl.h>
+#include <limits.h>
+#include <stdint.h>
+#include <stdio.h>
+#include <string.h>
+#include <unistd.h>
+#include <zlib.h>
+
+#define COMPRESSION_NONE 0x00
+#define COMPRESSION_DEFLATE 0x08
+
+#define MIN(a, b) ((a) < (b) ? (a) : (b))
+
+void *
+find_central_directory(uint8_t *addr, size_t len)
+{
+ uint32_t offset;
+ uint16_t clen;
+ uint8_t *p, *end;
+
+ /*
+ * At -22 bytes from the end there is the end of the central
+ * directory assuming an empty comment. It's a sensible place
+ * from which start.
+ */
+ if (len < 22)
+ return NULL;
+ end = addr + len;
+ p = end - 22;
+
+again:
+ for (; p > addr; --p)
+ if (memcmp(p, "\x50\x4b\x05\x06", 4) == 0)
+ break;
+
+ if (p == addr)
+ return NULL;
+
+ /* read comment length */
+ memcpy(&clen, p + 20, sizeof(clen));
+ clen = le16toh(clen);
+
+ /* false signature inside a comment? */
+ if (clen + 22 != end - p) {
+ p--;
+ goto again;
+ }
+
+ /* read the offset for the central directory */
+ memcpy(&offset, p + 16, sizeof(offset));
+ offset = le32toh(offset);
+
+ if (addr + offset > p)
+ return NULL;
+
+ return addr + offset;
+}
+
+void
+unzip_none(uint8_t *data, size_t size, unsigned long ocrc)
+{
+ unsigned long crc = 0;
+
+ fwrite(data, 1, size, stdout);
+
+ crc = crc32(0, data, size);
+ if (crc != ocrc)
+ errx(1, "CRC mismatch");
+}
+
+void
+unzip_deflate(uint8_t *data, size_t size, unsigned long ocrc)
+{
+ z_stream stream;
+ size_t have;
+ unsigned long crc = 0;
+ char buf[BUFSIZ];
+
+ stream.zalloc = Z_NULL;
+ stream.zfree = Z_NULL;
+ stream.opaque = Z_NULL;
+ stream.next_in = data;
+ stream.avail_in = size;
+ stream.next_out = Z_NULL;
+ stream.avail_out = 0;
+ if (inflateInit2(&stream, -15) != Z_OK)
+ err(1, "inflateInit failed");
+
+ do {
+ stream.next_out = buf;
+ stream.avail_out = sizeof(buf);
+
+ switch (inflate(&stream, Z_BLOCK)) {
+ case Z_STREAM_ERROR:
+ errx(1, "stream error");
+ case Z_NEED_DICT:
+ errx(1, "need dict");
+ case Z_DATA_ERROR:
+ errx(1, "data error: %s", stream.msg);
+ case Z_MEM_ERROR:
+ errx(1, "memory error");
+ }
+
+ have = sizeof(buf) - stream.avail_out;
+ fwrite(buf, 1, have, stdout);
+ crc = crc32(crc, buf, have);
+ } while (stream.avail_out == 0);
+
+ inflateEnd(&stream);
+
+ if (crc != ocrc)
+ errx(1, "CRC mismatch");
+}
+
+void
+unzip(uint8_t *zip, size_t len, uint8_t *entry)
+{
+ uint32_t size, osize, crc, off;
+ uint16_t flags, compression;
+ uint16_t flen, xlen;
+ uint8_t *data, *offset;
+
+ /* read the offset of the file record */
+ memcpy(&off, entry + 42, sizeof(off));
+ offset = zip + le32toh(off);
+
+ if (offset > zip + len - 4 ||
+ memcmp(offset, "\x50\x4b\x03\x04", 4) != 0)
+ errx(1, "invalid offset or file header signature");
+
+ memcpy(&flags, offset + 6, sizeof(flags));
+ memcpy(&compression, offset + 8, sizeof(compression));
+
+ flags = le16toh(flags);
+ compression = le16toh(compression);
+
+ memcpy(&crc, entry + 16, sizeof(crc));
+ memcpy(&size, entry + 20, sizeof(size));
+ memcpy(&osize, entry + 24, sizeof(osize));
+
+ crc = le32toh(crc);
+ size = le32toh(size);
+ osize = le32toh(osize);
+
+ memcpy(&flen, offset + 26, sizeof(flen));
+ memcpy(&xlen, offset + 28, sizeof(xlen));
+
+ flen = le16toh(flen);
+ xlen = le16toh(xlen);
+
+ data = offset + 30 + flen + xlen;
+ if (data + size > zip + len)
+ errx(1, "corrupted zip, offset out of file");
+
+ switch (compression) {
+ case COMPRESSION_NONE:
+ unzip_none(data, size, crc);
+ break;
+ case COMPRESSION_DEFLATE:
+ unzip_deflate(data, size, crc);
+ break;
+ default:
+ errx(1, "unknown compression method 0x%02x",
+ compression);
+ }
+}
+
+void *
+next(uint8_t *zip, size_t len, uint8_t *entry)
+{
+ uint16_t flen, xlen, clen;
+ uint8_t *next, *end;
+
+ memcpy(&flen, entry + 28, sizeof(flen));
+ memcpy(&xlen, entry + 28 + 2, sizeof(xlen));
+ memcpy(&clen, entry + 28 + 2 + 2, sizeof(xlen));
+
+ flen = le16toh(flen);
+ xlen = le16toh(xlen);
+ clen = le16toh(clen);
+
+ next = entry + 46 + flen + xlen + clen;
+ end = zip + len;
+ if (next >= end - 46 ||
+ memcmp(next, "\x50\x4b\x01\x02", 4) != 0)
+ return NULL;
+ return next;
+}
+
+void
+filename(uint8_t *zip, size_t len, uint8_t *entry, char *buf,
+ size_t size)
+{
+ uint16_t flen;
+ size_t s;
+
+ memcpy(&flen, entry + 28, sizeof(flen));
+ flen = le16toh(flen);
+
+ s = MIN(size-1, flen);
+ memcpy(buf, entry + 46, s);
+ buf[s] = '\0';
+}
+
+void
+ls(uint8_t *zip, size_t len, uint8_t *cd)
+{
+ char name[PATH_MAX];
+
+ do {
+ filename(zip, len, cd, name, sizeof(name));
+ printf("%s\n", name);
+ } while ((cd = next(zip, len, cd)) != NULL);
+}
+
+void *
+find_file(uint8_t *zip, size_t len, uint8_t *cd, const char *target)
+{
+ char name[PATH_MAX];
+
+ do {
+ filename(zip, len, cd, name, sizeof(name));
+ if (!strcmp(name, target))
+ return cd;
+ } while ((cd = next(zip, len, cd)) != NULL);
+
+ return NULL;
+}
+
+int
+extract_file(uint8_t *zip, size_t len, uint8_t *cd, const char *target)
+{
+ if ((cd = find_file(zip, len, cd, target)) == NULL)
+ return -1;
+
+ unzip(zip, len, cd);
+ return 0;
+}
+
+void *
+map_file(int fd, size_t *len)
+{
+ off_t jump;
+ void *addr;
+
+ if ((jump = lseek(fd, 0, SEEK_END)) == -1)
+ err(1, "lseek");
+
+ if (lseek(fd, 0, SEEK_SET) == -1)
+ err(1, "lseek");
+
+ if ((addr = mmap(NULL, jump, PROT_READ, MAP_PRIVATE, fd, 0))
+ == MAP_FAILED)
+ err(1, "mmap");
+
+ *len = jump;
+ return addr;
+}
+
+int
+main(int argc, char **argv)
+{
+ int i, fd;
+ void *zip, *cd;
+ size_t len;
+
+ if (argc < 2) {
+ fprintf(stderr, "Usage: %s archive.zip [files...]",
+ *argv);
+ return 1;
+ }
+
+ if ((fd = open(argv[1], O_RDONLY)) == -1)
+ err(1, "can't open %s", argv[1]);
+
+ zip = map_file(fd, &len);
+
+#ifdef __OpenBSD__
+ if (pledge("stdio", NULL) == -1)
+ err(1, "pledge");
+#endif
+
+ if ((cd = find_central_directory(zip, len)) == NULL)
+ errx(1, "can't find the central directory");
+
+ if (argc == 2)
+ ls(zip, len, cd);
+ else {
+ for (i = 2; i < argc; ++i)
+ extract_file(zip, len, cd, argv[i]);
+ }
+
+ munmap(zip, len);
+ close(fd);
+
+ return 0;
+}
Omar Polo