all: relax compiler requirements

- Do not check __STDC_HOSTED__.
- Do not use atomic builtins.
- Do not use thread-local storage for PRNG state.

src/defs.h

@@ -23,8 +23,7 @@
 #ifndef BOOKMARKFS_DEFS_H_
 #define BOOKMARKFS_DEFS_H_
 
-#if !defined(__STDC_VERSION__) || (__STDC_VERSION__ < 199901L)  \
-     || (__STDC_HOSTED__ != 1)
+#if !defined(__STDC_VERSION__) || (__STDC_VERSION__ < 199901L)
 #  error "unsupported compiler"
 #elif __STDC_VERSION__ >= 202311L
 #  define HAVE_STDC_23  1

src/json.h

@@ -25,6 +25,13 @@
 
 #include <string.h>
 
+// No need for atomic json_incref()/json_decref(),
+// since we're only using Jansson in a single thread.
+#include <jansson_config.h>
+#undef  JSON_HAVE_ATOMIC_BUILTINS
+#define JSON_HAVE_ATOMIC_BUILTINS  0
+#undef  JSON_HAVE_SYNC_BUILTINS
+#define JSON_HAVE_SYNC_BUILTINS  0
 #include <jansson.h>
 
 // The following helper macros are useful with literal keys,

src/prng.c

@@ -39,10 +39,7 @@
 static uint64_t rotl64 (uint64_t, unsigned);
 // Forward declaration end
 
-#ifndef BOOKMARKFS_TLS
-#  error "compiler does not support thread-local storage"
-#endif
-static BOOKMARKFS_TLS uint64_t state[4];
+static uint64_t state[4];
 
 static uint64_t
 rotl64 (

src/prng.h

@@ -31,7 +31,7 @@
  * Returns a pseudo-random 64-bit unsigned integer.
  * The PRNG should be seeded before calling this function.
  *
- * This function is MT-Safe.
+ * This function is MT-Unsafe.
  */
 uint64_t
 prng_rand (void);
@@ -40,9 +40,6 @@ prng_rand (void);
  * Seed the PRNG with the given values.
  * If `s` is NULL, the values will be read from /dev/urandom.
  *
- * When used in a multi-threaded environment,
- * each thread should seed the PRNG separately.
- *
  * Returns 0 on success, -1 on failure.
  * If `s` is not NULL, this function never fails.
  */