From 02266b4dea10f6c0aa2a88ba232b690ba410d34e Mon Sep 17 00:00:00 2001
From: icst <icst@no.email>
Date: Sun, 7 Jul 2024 22:28:22 -0400
Subject: [PATCH] c-hdr-parser: add header open and syntax validation checks

---
 c-hdr-parser.c | 71 +++++++++++++++++++++++++++++++++++++++++++++++++-
 1 file changed, 70 insertions(+), 1 deletion(-)

diff --git a/c-hdr-parser.c b/c-hdr-parser.c
index 1280a91..310068f 100644
--- a/c-hdr-parser.c
+++ b/c-hdr-parser.c
@@ -4,6 +4,7 @@
 #include <ctype.h>
 #include <assert.h>
 #include <stdint.h>
+#include <unistd.h> /*close()*/
 
 /// realloc s1 and append s2 to it (modifies only s1)
 char *cstr_append(char *s1, const char *s2) {
@@ -37,6 +38,62 @@ FILE *open_c_header(const char *cc_cmd, const char *hdr_fn) {
     return f;
 }
 
+/**
+ * Run a header file through the compiler to validate it's syntax
+ */
+int valid_c_header(const char *cc_cmd, const char *hdr_fn) {
+
+    static const char tmppath[] = "/tmp/.";
+
+    char *test_fn = strdup(tmppath);
+    if ( test_fn == NULL ) return 0;
+    test_fn = cstr_append(test_fn, hdr_fn);
+    if ( test_fn == NULL ) return 0;
+    test_fn = cstr_append(test_fn, ".o.XXXXXX");
+    if ( test_fn == NULL ) return 0;
+
+    // NOTE: This generates a unique filename by replacing the 'XXXXXX' with random chars then
+    // opens the file. It MODIFIES its argument string to contain the random chars selected to
+    // replace the 'XXXXXX' so after call if the filedesc is valid, test_fn is the true filename.
+    int r = mkstemp(test_fn);
+    if ( r == -1 ) {
+        free( test_fn );
+        return 0;
+    }
+
+    close(r);
+
+    char *cmd = strdup("echo \"#include <");
+    if ( cmd == NULL ) goto FAILRET;
+    cmd = cstr_append(cmd, hdr_fn);
+    if ( cmd == NULL ) goto FAILRET;
+    cmd = cstr_append(cmd, ">\" | ");
+    if ( cmd == NULL ) goto FAILRET;
+    cmd = cstr_append(cmd, cc_cmd);
+    if ( cmd == NULL ) goto FAILRET;
+    cmd = cstr_append(cmd, " -I . -c -x c -o "); /*include ./; compile only, don't link; c syntax*/
+    if ( cmd == NULL ) goto FAILRET;
+    cmd = cstr_append(cmd, test_fn);
+    if ( cmd == NULL ) goto FAILRET;
+    cmd = cstr_append(cmd, "  -"); /*use stdin*/
+    if ( cmd == NULL ) goto FAILRET;
+
+    puts(cmd);
+
+    int ret = system(cmd);
+
+    remove( test_fn );
+    free( test_fn );
+    free( cmd );
+
+    return (ret == 0);
+FAILRET:
+    remove( test_fn );
+    free( test_fn );
+    if ( cmd ) free( cmd );
+    return 0;
+}
+
 /// Parse a series of keywords/identifiers until a non-kw/id is found indicating the end
 char ** parse_c_header_identkws(size_t *nidkws, int *c, FILE *f) {
 
@@ -559,8 +616,9 @@ int main(int argc, char *argv[]) {
     if ( argc <= 1 ) return 1;
 
     const char *cmd = getenv("CC");
+    cmd = (cmd == NULL) ? "cc" : cmd;
 
-    FILE *fhdr = open_c_header(((cmd == NULL) ? "cc" : cmd), argv[1]);
+    FILE *fhdr = open_c_header(cmd, argv[1]);
 
     if ( fhdr == NULL ) {
         perror(argv[1]);
@@ -570,6 +628,17 @@ int main(int argc, char *argv[]) {
     size_t ndecl = 0;
     char **decl = parse_c_header(&ndecl, fhdr);
 
+    int r = pclose(fhdr);
+    if ( r != 0 ) {
+        fprintf(stdout, "[ERROR] Failed to read c-header '%s', CC=%s returned %d\n", argv[1], cmd, r);
+        return 1;
+    }
+
+    if ( !valid_c_header(cmd, argv[1]) ) {
+        fprintf(stdout, "[ERROR] System CC=%s failed to validate the syntax of c-header: %s\n", cmd, argv[1]);
+        return 1;
+    }
+
     for (size_t n=0; n < ndecl; n++) {
         puts(decl[n]);
     }