Add Makefile and demo app

The demo app can list contents and extract tar files using
microtar, and serves to demonstrate the API.

3 files changed, 215 insertions, 0 deletions

diff --git a/.gitignore b/.gitignore
new file mode 100644
index 0000000..cccd994
--- /dev/null
+++ b/.gitignore
@@ -0,0 +1,3 @@
+*.o
+*.a
+/mtar
diff --git a/Makefile b/Makefile
new file mode 100644
index 0000000..b2142ec
--- /dev/null
+++ b/Makefile
@@ -0,0 +1,21 @@
+CPPFLAGS = -Isrc
+CFLAGS = -std=c99 -Wall -Wextra
+
+MTAR_OBJ = mtar.o
+MTAR_BIN = mtar
+
+MICROTAR_OBJ = src/microtar.o src/microtar-stdio.o
+MICROTAR_LIB = libmicrotar.a
+
+$(MTAR_BIN): $(MTAR_OBJ) $(MICROTAR_LIB)
+	$(CC) $(CFLAGS) $(CPPFLAGS) -o $@ $^
+
+$(MICROTAR_LIB): $(MICROTAR_OBJ)
+	$(AR) r $@ $^
+
+%.o: %.c
+	$(CC) $(CFLAGS) $(CPPFLAGS) -c $< -o $@
+
+clean:
+	rm -f $(MICROTAR_LIB) $(MICROTAR_OBJ)
+	rm -f $(MTAR_BIN) $(MTAR_OBJ)
diff --git a/mtar.c b/mtar.c
new file mode 100644
index 0000000..580c68d
--- /dev/null
+++ b/mtar.c
@@ -0,0 +1,191 @@
+/*
+ * Copyright (c) 2021 Aidan MacDonald
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to
+ * deal in the Software without restriction, including without limitation the
+ * rights to use, copy, modify, merge, publish, distribute, sublicense, and/or
+ * sell copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * 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 OR COPYRIGHT HOLDERS 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.
+ */
+
+#include "microtar.h"
+#include <stdio.h>
+#include <string.h>
+#include <stdlib.h>
+#include <stdarg.h>
+#include <sys/stat.h>
+#include <fcntl.h>
+#include <errno.h>
+#include <unistd.h>
+
+/* exit codes */
+#define E_TAR   1
+#define E_FS    2
+#define E_OTHER 4
+#define E_ARGS  8
+
+enum {
+    OP_LIST,
+    OP_CREATE,
+    OP_EXTRACT,
+};
+
+void die(int err, const char* msg, ...)
+{
+    fprintf(stderr, "mtar: ");
+
+    va_list ap;
+    va_start(ap, msg);
+    vfprintf(stderr, msg, ap);
+    va_end(ap);
+
+    fprintf(stderr, "\n");
+    exit(err);
+}
+
+int list_foreach_cb(mtar_t* tar, const mtar_header_t* h, void* arg)
+{
+    (void)tar;
+    (void)arg;
+    printf("%s\n", h->name);
+    return 0;
+}
+
+void list_files(mtar_t* tar)
+{
+    int err = mtar_foreach(tar, list_foreach_cb, NULL);
+    if(err)
+        die(E_TAR, "listing failed: %s", mtar_strerror(err));
+}
+
+struct extract_args {
+    char** names;
+    int count;
+};
+
+int extract_foreach_cb(mtar_t* tar, const mtar_header_t* h, void* arg)
+{
+    struct extract_args* args = arg;
+    (void)args; /* TODO */
+
+    if(h->type == MTAR_TDIR) {
+        if(mkdir(h->name, h->mode) != 0)
+            die(E_FS, "cannot create directory \"%s\"", h->name);
+        return 0;
+    }
+
+    if(h->type != MTAR_TREG) {
+        fprintf(stderr, "warning: not extracting unsupported type \"%s\"", h->name);
+        return 0;
+    }
+
+    int fd = open(h->name, O_CREAT|O_WRONLY, h->mode);
+    if(fd < 0)
+        die(E_FS, "extracting \"%s\" failed: %s", h->name, strerror(errno));
+
+    char iobuf[1024];
+    while(!mtar_eof_data(tar)) {
+        int rcount = mtar_read_data(tar, iobuf, sizeof(iobuf));
+        if(rcount < 0)
+            die(E_TAR, "extracting \"%s\" failed: %s", h->name, mtar_strerror(rcount));
+
+        int wcount = write(fd, iobuf, rcount);
+        if(wcount != rcount)
+            die(E_FS, "extracting \"%s\" failed: %s", h->name, strerror(errno));
+    }
+
+    close(fd);
+    return 0;
+}
+
+void extract_files(mtar_t* tar, char** files, int num_files)
+{
+    struct extract_args args;
+    args.names = files;
+    args.count = num_files;
+
+    int err = mtar_foreach(tar, extract_foreach_cb, &args);
+    if(err)
+        die(E_TAR, "extraction failed: %s", mtar_strerror(err));
+}
+
+int main(int argc, char* argv[])
+{
+    ++argv, --argc;
+    if(argc == 0)
+        die(E_ARGS, "no input files");
+
+    if(!strcmp(*argv, "--help")) {
+        printf(
+"usage:\n"
+"  mtar list tar-file\n"
+"    List the members of the given tar archive, one filename per line.\n"
+"\n"
+"  mtar create tar-file members...\n"
+"  mtar add tar-file members...\n"
+"    Create a new tar archive from the files listed on the command line.\n"
+"    WARNING: Any existing file at tar-file will be overwritten!\n"
+"\n"
+"  mtar extract tar-file [members...]\n"
+"    Extract the contents of the tar archive to the current directory.\n"
+"    If filenames are given, only the named members will be extracted.\n"
+"\n");
+        exit(E_ARGS);
+    }
+
+    int op;
+    if(!strcmp(*argv, "list"))
+        op = OP_LIST;
+    else if(!strcmp(*argv, "create"))
+        op = OP_CREATE;
+    else if(!strcmp(*argv, "extract"))
+        op = OP_EXTRACT;
+    else
+        die(E_ARGS, "invalid operation \"%s\"", *argv);
+    ++argv, --argc;
+
+    if(argc == 0)
+        die(E_ARGS, "missing archive name");
+    const char* archive_name = *argv;
+    ++argv, --argc;
+
+    if(op == OP_LIST && argc != 0)
+        die(E_ARGS, "excess arguments on command line");
+
+    mtar_t tar;
+    int err = mtar_open(&tar, archive_name, "rb");
+    if(err)
+        die(E_TAR, "can't open archive: %s", mtar_strerror(err));
+
+    switch(op) {
+    case OP_LIST:
+        list_files(&tar);
+        break;
+
+    case OP_EXTRACT:
+        extract_files(&tar, argv, argc);
+        break;
+
+    default:
+        die(E_OTHER, "not implemented");
+        break;
+    }
+
+    err = mtar_close(&tar);
+    if(err)
+        die(E_TAR, "failed to finalize archive: %s", mtar_strerror(err));
+
+    return 0;
+}