fs_config_generate: add -P <partitionlist> option

Add a -P option to fs_config_generate that allows us to filter on
a comma separated partition whitelist or minus prefixed -blacklist.
A partition is defined as accessible as <partition>/ or
system/<partition>/.

No change for legacy, where no -P flag is specified.

For system.img, but not vendor, oem or odm file references:
fs_config_generate -P -vendor,-oem,-odm

For vendor.img file references:
fs_config_generate -P vendor

For oem.img file references:
fs_config_generate -P oem

For odm.img file references:
fs_config_generate -P odm

Add and fortify tests for each of these cases.

SideEffects: none
Test: gTest host fs_config-unit-test
Bug: 36071012
Change-Id: I0537453bb289d41ef98ad76e69f78ae49358a1b3
diff --git a/tools/fs_config/fs_config_generate.c b/tools/fs_config/fs_config_generate.c
index e08642f..cb7ff9d 100644
--- a/tools/fs_config/fs_config_generate.c
+++ b/tools/fs_config/fs_config_generate.c
@@ -14,9 +14,11 @@
  * limitations under the License.
  */
 
+#include <ctype.h>
 #include <stdbool.h>
 #include <stdio.h>
 #include <stdlib.h>
+#include <string.h>
 #include <unistd.h>
 
 #include <private/android_filesystem_config.h>
@@ -35,35 +37,50 @@
 #endif
 
 #ifdef NO_ANDROID_FILESYSTEM_CONFIG_DEVICE_DIRS
-  static const struct fs_path_config android_device_dirs[] = {
-};
+static const struct fs_path_config android_device_dirs[] = { };
 #endif
 
 #ifdef NO_ANDROID_FILESYSTEM_CONFIG_DEVICE_FILES
 static const struct fs_path_config android_device_files[] = {
 #ifdef NO_ANDROID_FILESYSTEM_CONFIG_DEVICE_DIRS
-    { 0, AID_ROOT, AID_ROOT, 0, "system/etc/fs_config_dirs" },
+    {0000, AID_ROOT, AID_ROOT, 0, "system/etc/fs_config_dirs"},
+    {0000, AID_ROOT, AID_ROOT, 0, "vendor/etc/fs_config_dirs"},
+    {0000, AID_ROOT, AID_ROOT, 0, "oem/etc/fs_config_dirs"},
+    {0000, AID_ROOT, AID_ROOT, 0, "odm/etc/fs_config_dirs"},
 #endif
-    { 0, AID_ROOT, AID_ROOT, 0, "system/etc/fs_config_files" },
+    {0000, AID_ROOT, AID_ROOT, 0, "system/etc/fs_config_files"},
+    {0000, AID_ROOT, AID_ROOT, 0, "vendor/etc/fs_config_files"},
+    {0000, AID_ROOT, AID_ROOT, 0, "oem/etc/fs_config_files"},
+    {0000, AID_ROOT, AID_ROOT, 0, "odm/etc/fs_config_files"},
 };
 #endif
 
 static void usage() {
   fprintf(stderr,
     "Generate binary content for fs_config_dirs (-D) and fs_config_files (-F)\n"
-    "from device-specific android_filesystem_config.h override\n\n"
-    "Usage: fs_config_generate -D|-F [-o output-file]\n");
+    "from device-specific android_filesystem_config.h override.  Filter based\n"
+    "on a comma separated partition list (-P) whitelist or prefixed by a\n"
+    "minus blacklist.  Partitions are identified as path references to\n"
+    "<partition>/ or system/<partition>/\n\n"
+    "Usage: fs_config_generate -D|-F [-P list] [-o output-file]\n");
 }
 
-int main(int argc, char** argv) {
-  const struct fs_path_config *pc;
-  const struct fs_path_config *end;
-  bool dir = false, file = false;
-  FILE *fp = stdout;
-  int opt;
+/* If tool switches to C++, use android-base/macros.h array_size() */
+#ifndef ARRAY_SIZE /* popular macro */
+#define ARRAY_SIZE(x) (sizeof(x) / sizeof((x)[0]))
+#endif
 
-  while((opt = getopt(argc, argv, "DFho:")) != -1) {
-    switch(opt) {
+int main(int argc, char** argv) {
+  const struct fs_path_config* pc;
+  const struct fs_path_config* end;
+  bool dir = false, file = false;
+  const char* partitions = NULL;
+  FILE* fp = stdout;
+  int opt;
+  static const char optstring[] = "DFP:ho:";
+
+  while ((opt = getopt(argc, argv, optstring)) != -1) {
+    switch (opt) {
     case 'D':
       if (file) {
         fprintf(stderr, "Must specify only -D or -F\n");
@@ -80,6 +97,30 @@
       }
       file = true;
       break;
+    case 'P':
+      if (partitions) {
+        fprintf(stderr, "Specify only one partition list\n");
+        usage();
+        exit(EXIT_FAILURE);
+      }
+      while (*optarg && isspace(*optarg)) ++optarg;
+      if (!optarg[0]) {
+        fprintf(stderr, "Partition list empty\n");
+        usage();
+        exit(EXIT_FAILURE);
+      }
+      if (!optarg[1]) {
+        fprintf(stderr, "Partition list too short \"%s\"\n", optarg);
+        usage();
+        exit(EXIT_FAILURE);
+      }
+      if ((optarg[0] == '-') && strchr(optstring, optarg[1]) && !optarg[2]) {
+        fprintf(stderr, "Partition list is a flag \"%s\"\n", optarg);
+        usage();
+        exit(EXIT_FAILURE);
+      }
+      partitions = optarg;
+      break;
     case 'o':
       if (fp != stdout) {
         fprintf(stderr, "Specify only one output file\n");
@@ -101,6 +142,12 @@
     }
   }
 
+  if (optind < argc) {
+    fprintf(stderr, "Unknown non-argument \"%s\"\n", argv[optind]);
+    usage();
+    exit(EXIT_FAILURE);
+  }
+
   if (!file && !dir) {
     fprintf(stderr, "Must specify either -F or -D\n");
     usage();
@@ -109,19 +156,64 @@
 
   if (dir) {
     pc = android_device_dirs;
-    end = &android_device_dirs[sizeof(android_device_dirs) / sizeof(android_device_dirs[0])];
+    end = &android_device_dirs[ARRAY_SIZE(android_device_dirs)];
   } else {
     pc = android_device_files;
-    end = &android_device_files[sizeof(android_device_files) / sizeof(android_device_files[0])];
+    end = &android_device_files[ARRAY_SIZE(android_device_files)];
   }
-  for(; (pc < end) && pc->prefix; pc++) {
+  for (; (pc < end) && pc->prefix; pc++) {
+    bool submit;
     char buffer[512];
     ssize_t len = fs_config_generate(buffer, sizeof(buffer), pc);
     if (len < 0) {
       fprintf(stderr, "Entry too large\n");
       exit(EXIT_FAILURE);
     }
-    if (fwrite(buffer, 1, len, fp) != (size_t)len) {
+    submit = true;
+    if (partitions) {
+      char* partitions_copy = strdup(partitions);
+      char* arg = partitions_copy;
+      char* sv = NULL; /* Do not leave uninitialized, NULL is known safe. */
+      /* Deal with case all iterated partitions are blacklists with no match */
+      bool all_blacklist_but_no_match = true;
+      submit = false;
+
+      if (!partitions_copy) {
+        fprintf(stderr, "Failed to allocate a copy of %s\n", partitions);
+        exit(EXIT_FAILURE);
+      }
+      /* iterate through (officially) comma separated list of partitions */
+      while (!!(arg = strtok_r(arg, ",:; \t\n\r\f", &sv))) {
+        static const char system[] = "system/";
+        size_t plen;
+        bool blacklist = false;
+        if (*arg == '-') {
+          blacklist = true;
+          ++arg;
+        } else {
+          all_blacklist_but_no_match = false;
+        }
+        plen = strlen(arg);
+        /* deal with evil callers */
+        while (arg[plen - 1] == '/') {
+          --plen;
+        }
+        /* check if we have <partition>/ or /system/<partition>/ */
+        if ((!strncmp(pc->prefix, arg, plen) && (pc->prefix[plen] == '/')) ||
+            (!strncmp(pc->prefix, system, strlen(system)) &&
+             !strncmp(pc->prefix + strlen(system), arg, plen) &&
+             (pc->prefix[strlen(system) + plen] == '/'))) {
+          all_blacklist_but_no_match = false;
+          /* we have a match !!! */
+          if (!blacklist) submit = true;
+          break;
+        }
+        arg = NULL;
+      }
+      free(partitions_copy);
+      if (all_blacklist_but_no_match) submit = true;
+    }
+    if (submit && (fwrite(buffer, 1, len, fp) != (size_t)len)) {
       fprintf(stderr, "Write failure\n");
       exit(EXIT_FAILURE);
     }