dejsonlz4: initial code commit

LICENSE

@@ -1,4 +1,4 @@
-Copyright (c) 2016, avih
+Copyright (C) 2016, Avi Halachmi (:avih)
 All rights reserved.
 
 Redistribution and use in source and binary forms, with or without

README.md

@@ -1,2 +1,22 @@
 # dejsonlz4
-Unofficial decompressor for Mozilla bookmark backup files
+Decompressor for Mozilla/Firefox bookmark backup files
+
+Mozilla Firefox currently uses unofficial lz4 compression for bookmark backup files,
+and `dejsonlz4` can currently be used to decompress them. These files have an extension `.jsonlz4`.
+
+This repository includes verbatim copies of `lz4.c` and `lz4.h` from the Mozilla repository
+as of 2016-05-16 (as currently used by Firefox).
+
+## Usage:
+```
+Usage: dejsonlz4 [-h] IN_FILE [OUT_FILE]
+   -h: Display this help and exit.
+Decompress Mozilla bookmark backup file IN_FILE to OUT_FILE.
+If OUT_FILE is not provided or is '-' then decompress to standard output.
+```
+
+## Build:
+- `gcc -Wall -o dejsonlz4 dejsonlz4.c lz4.c`
+
+## Windows note:
+- `dejsonlz4` currently does not support unicode file names, for the sake of simpler code.

src/dejsonlz4.c

@@ -0,0 +1,163 @@
+/*
+   dejsonlz4 - Decompress Mozilla bookmark backup files
+   Copyright (C) 2016, Avi Halachmi
+   BSD 2-Clause License (http://www.opensource.org/licenses/bsd-license.php)
+
+   Redistribution and use in source and binary forms, with or without
+   modification, are permitted provided that the following conditions are
+   met:
+
+       * Redistributions of source code must retain the above copyright
+   notice, this list of conditions and the following disclaimer.
+       * Redistributions in binary form must reproduce the above
+   copyright notice, this list of conditions and the following disclaimer
+   in the documentation and/or other materials provided with the
+   distribution.
+
+   THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+   "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+   LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+   A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+   OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+   SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+   LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+   DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+   THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+   (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+   OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+   You can contact the author at :
+   - Repository: https://github.com/avih/dejsonlz4
+*/
+
+/*
+   lz4.c and lz4.h are verbatim copies from Mozilla source tree mfbt/lz4.*
+   (Mercurial) rev: c3f5e6079284 (2016-05-16) and carry their own license.
+*/
+
+/* Build: gcc -Wall -o dejsonlz4 dejsonlz4.c lz4.c */
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <fcntl.h>
+#include <string.h>
+
+#include "lz4.h"
+
+const char mozlz4_magic[] = {109, 111, 122, 76, 122, 52, 48, 0};  /* "mozLz40\0" */
+const int decomp_size = 4;  /* 4 bytes size come after the header */
+
+void exit_usage(int code) {
+    fprintf((code ? stderr : stdout), "%s",
+"Usage: dejsonlz4 [-h] IN_FILE [OUT_FILE]\n"
+"   -h: Display this help and exit.\n"
+"Decompress Mozilla bookmark backup file IN_FILE to OUT_FILE.\n"
+"If OUT_FILE is not provided or is '-' then decompress to standard output.\n"
+           );
+    exit(code);
+}
+
+void *file_to_mem(const char *fname, size_t *out_size)
+{
+    size_t fsize = 0;
+    void *rv = 0;
+    FILE *f = fopen(fname, "rb");
+    if (!f)
+        goto cleanup;
+    if (fseek(f, 0, SEEK_END) < 0)
+        goto cleanup;
+    fsize = ftell(f);
+    fseek(f, 0, SEEK_SET);
+    if (!(rv = malloc(fsize)))
+        goto cleanup;
+    if (fsize != fread(rv, 1, fsize, f)) {
+        free(rv);
+        rv = 0;
+    }
+
+cleanup:
+    if (f)
+        fclose(f);
+    if (rv && out_size)
+        *out_size = fsize;
+    return rv;
+}
+
+const size_t magic_size = sizeof mozlz4_magic;
+
+int main(int argc, char **argv)
+{
+    size_t isize = 0, osize = 0;
+    const char *iname = 0, *oname = 0;
+    char *idata = 0, *odata = 0;
+    FILE *ofile = 0;
+    int rv = 1, dsize = -1, i;
+
+    if ((argc > 3) || (argc < 2) || (argc > 1 && !strcmp(argv[1], "-h")))
+        exit_usage(argc == 2 ? 0 : 1);
+    if (argc > 1)
+        iname = argv[1];
+    if (argc > 2 && strcmp("-", argv[2]))
+        oname = argv[2];
+
+    if (!(idata = file_to_mem(iname, &isize))) {
+        fprintf(stderr, "Error: cannot read file '%s'\n", iname);
+        goto cleanup;
+    }
+
+    i = 0;
+    while (i < isize && i < magic_size && idata[i] == mozlz4_magic[i])
+        i++;
+    if (i != magic_size || isize < magic_size + decomp_size) {
+        fprintf(stderr, "Error: incorrect header or file too small\n");
+        goto cleanup;
+    }
+    while (i < magic_size + decomp_size) {
+        osize += (unsigned char)idata[i] << (8 * (i - magic_size));
+        i++;
+    }
+
+    if (!(odata = malloc(osize))) {
+        fprintf(stderr, "Error: cannot allocate memory for output\n");
+        goto cleanup;
+    }
+    if ((dsize = LZ4_decompress_safe(idata + i, odata, isize - i, osize)) < 0) {
+        fprintf(stderr, "Error: decompression failed: %d\n", dsize);
+        goto cleanup;
+    }
+    if (dsize != osize)
+        fprintf(stderr, "Warning: decompressed file smaller than expected\n");
+
+    if (oname) {
+        if (!(ofile = fopen(oname, "wb"))) {
+            fprintf(stderr, "Error: cannot open '%s' for writing\n", oname);
+            goto cleanup;
+        }
+    } else {
+#ifdef _WIN32
+        /* Try changing stdout to binary mode, or else it messes with EOL chars.
+         * Might not matter much for Mozilla files since they're text.
+         */
+        if (_setmode(_fileno(stdout), O_BINARY) == -1)
+            fprintf(stderr, "Warning: cannot set output to binary mode\n");
+#endif
+        ofile = stdout;
+    }
+
+    if (dsize != fwrite(odata, 1, dsize, ofile)) {
+        fprintf(stderr, "Error: cannot write to '%s'\n", oname ? oname : "<stdout>");
+        goto cleanup;
+    }
+
+    rv = 0;
+
+cleanup:
+    if (ofile && oname)
+        fclose(ofile);
+    if (odata)
+        free(odata);
+    if (idata)
+        free(idata);
+
+    return rv;
+}