on read: provide text "path: {source_path}" instead of actual file content

rgpgfs.c

@@ -1,16 +1,64 @@
 #include <errno.h>
 #include <stdio.h>
+#include <stdlib.h>
 #include <string.h>
 
 // posix
 #include <dirent.h>
 #include <sys/stat.h>
+#include <sys/types.h>
 #include <unistd.h>
 
 // http://libfuse.github.io/doxygen/globals.html
 #define FUSE_USE_VERSION 31
 #include <fuse.h>
 
+#define FUSE_PATH_BUF_LEN 256
+static char cache_dir[] = "/tmp/rgpgfs-cache-XXXXXX";
+static const size_t CACHE_PATH_BUF_LEN = sizeof(cache_dir) + FUSE_PATH_BUF_LEN;
+
+static int rgpgfs_mkdirs(char *path) {
+  char *delimiter = strrchr(path, '/');
+  if (delimiter == NULL) {
+    errno = ENOTSUP;
+    return 1;
+  }
+  *delimiter = '\0';
+  struct stat statbuf;
+  if (lstat(path, &statbuf) && (rgpgfs_mkdirs(path) || mkdir(path, S_IRWXU))) {
+    *delimiter = '/';
+    return 1;
+  }
+  *delimiter = '/';
+  return 0;
+}
+
+static int rgpgfs_encrypt(const char *source_path, char *cache_path) {
+  size_t source_path_len = strnlen(source_path, FUSE_PATH_BUF_LEN);
+  if (source_path_len >= FUSE_PATH_BUF_LEN) {
+    errno = ENAMETOOLONG;
+    perror("rgpgfs_encrypt");
+    return 1;
+  }
+  strcpy(cache_path, cache_dir);
+  strcpy(&cache_path[sizeof(cache_dir) - 1], source_path);
+
+  if (rgpgfs_mkdirs(cache_path)) {
+    perror("rgpgfs_encrypt: failed to create dirs");
+    return 1;
+  }
+
+  FILE *cache_file = fopen(cache_path, "w");
+  if (cache_file == NULL) {
+    perror("rgpgfs_encrypt: failed to open cache file");
+    return 1;
+  }
+  fprintf(cache_file, "path: %s\n", cache_path);
+  fclose(cache_file);
+
+  return 0;
+}
+
 static int rgpgfs_getattr(const char *path, struct stat *statbuf,
                           struct fuse_file_info *fi) {
   int res = lstat(path, statbuf);
@@ -49,11 +97,13 @@ static int rgpgfs_readdir(const char *path, void *buf, fuse_fill_dir_t filler,
   return 0;
 }
 
-static int rgpgfs_open(const char *path, struct fuse_file_info *fi) {
-  int res = open(path, fi->flags);
+static int rgpgfs_open(const char *source_path, struct fuse_file_info *fi) {
+  char cache_path[CACHE_PATH_BUF_LEN];
+  if (rgpgfs_encrypt(source_path, cache_path))
+    return -errno;
+  int res = open(cache_path, fi->flags);
   if (res == -1)
     return -errno;
-
   fi->fh = res;
   return 0;
 }
@@ -84,5 +134,10 @@ static struct fuse_operations rgpgfs_fuse_operations = {
 };
 
 int main(int argc, char *argv[]) {
+  if (mkdtemp(cache_dir) == NULL) {
+    return 1;
+  }
+  printf("cache: %s\n", cache_dir);
+  // TODO rm -r cache_dir (see man nftw)
   return fuse_main(argc, argv, &rgpgfs_fuse_operations, NULL);
 }