Move functions from process to file

Move filesystem-related functions from process.[ch] to file.[ch].

app/src/util/file.c

@@ -0,0 +1,48 @@
+#include "file.h"
+
+#include <stdlib.h>
+#include <string.h>
+
+#include "util/log.h"
+
+char *
+get_local_file_path(const char *name) {
+    char *executable_path = get_executable_path();
+    if (!executable_path) {
+        return NULL;
+    }
+
+    // dirname() does not work correctly everywhere, so get the parent
+    // directory manually.
+    // See <https://github.com/Genymobile/scrcpy/issues/2619>
+    char *p = strrchr(executable_path, PATH_SEPARATOR);
+    if (!p) {
+        LOGE("Unexpected executable path: \"%s\" (it should contain a '%c')",
+             executable_path, PATH_SEPARATOR);
+        free(executable_path);
+        return NULL;
+    }
+
+    *p = '\0'; // modify executable_path in place
+    char *dir = executable_path;
+    size_t dirlen = strlen(dir);
+    size_t namelen = strlen(name);
+
+    size_t len = dirlen + namelen + 2; // +2: '/' and '\0'
+    char *file_path = malloc(len);
+    if (!file_path) {
+        LOGE("Could not alloc path");
+        free(executable_path);
+        return NULL;
+    }
+
+    memcpy(file_path, dir, dirlen);
+    file_path[dirlen] = PATH_SEPARATOR;
+    // namelen + 1 to copy the final '\0'
+    memcpy(&file_path[dirlen + 1], name, namelen + 1);
+
+    free(executable_path);
+
+    return file_path;
+}
+