Eliminate exit(1) calls in LBT (#104)

It is rather rude of us to call `exit(1)` in our code, no matter how
rare it is.  Instead, we do our best to set ourselves into stable states
when these situations (many of which should be impossible) occur.

Author: staticfloat

src/autodetection.c

@@ -72,13 +72,19 @@ int32_t autodetect_blas_interface(void * isamax_addr) {
 
     // Override `lsame_` to point to our `fake_lsame` if we're unable to `RTLD_DEEPBIND`
     if (use_deepbind == 0) {
-        push_fake_lsame();
+        if (!push_fake_lsame()) {
+            // Bad LBT compile?
+            return LBT_INTERFACE_UNKNOWN;
+        }
     }
 
     int64_t max_idx = isamax(&n, X, &incx);
 
     if (use_deepbind == 0) {
-        pop_fake_lsame();
+        if (!pop_fake_lsame()) {
+            // Bad LBT compile?
+            return LBT_INTERFACE_UNKNOWN;
+        }
     }
 
     // Although we declare that `isamax` returns an `int64_t`, it may not actually do so,

src/deepbindless.c

@@ -18,14 +18,15 @@ LBT_DLLEXPORT uint8_t lbt_get_use_deepbind() {
 
 int lsame_idx = -1;
 const void *old_lsame32 = NULL, *old_lsame64 = NULL;
-void push_fake_lsame() {
+uint8_t push_fake_lsame() {
     // Find `lsame_` in our symbol list (if we haven't done so before)
     if (lsame_idx == -1) {
         lsame_idx = find_symbol_idx("lsame_");
         if (lsame_idx == -1) {
-            // This is fatal as it signifies a configuration error in our trampoline symbol list
-            fprintf(stderr, "Error: Unable to find lsame_ in our symbol list?!\n");
-            exit(1);
+            fprintf(stderr, "Error: Unable to find lsame_ in our symbol list. "
+                            "This signifies a libblastrampoline compilation failure. "
+                            "Aborting interface autodetection.\n");
+            return 0;
         }
     }
 
@@ -36,20 +37,23 @@ void push_fake_lsame() {
     // Insert our "fake" lsame in so that we always have a half-functional copy
     (*exported_func32_addrs[lsame_idx]) = &fake_lsame;
     (*exported_func64_addrs[lsame_idx]) = &fake_lsame;
+    return 1;
 }
 
-void pop_fake_lsame() {
+uint8_t pop_fake_lsame() {
     if (lsame_idx == -1) {
         // Did you call `pop_fake_lsame()` without calling `push_fake_lsame()` first?!
-        fprintf(stderr, "pop_fake_lsame() called with invalid `lsame_idx`!\n");
-        exit(1);
+        fprintf(stderr, "Error: Invalid lsame_ index. This is an internal libblastrampoline error. "
+                        "Aborting interface autodetection.\n");
+        return 0;
     }
 
     (*exported_func32_addrs[lsame_idx]) = old_lsame32;
     (*exported_func64_addrs[lsame_idx]) = old_lsame64;
 
     old_lsame32 = NULL;
     old_lsame64 = NULL;
+    return 1;
 }
 
 

src/dl_utils.c

@@ -31,7 +31,7 @@ void * load_library(const char * path) {
     wchar_t wpath[2*PATH_MAX + 1] = {0};
     if (!utf8_to_wchar(path, wpath, 2*PATH_MAX)) {
         fprintf(stderr, "ERROR: Unable to convert path %s to wide string!\n", path);
-        exit(1);
+        return NULL;
     }
     new_handle = (void *)LoadLibraryExW(wpath, NULL, LOAD_WITH_ALTERED_SEARCH_PATH);
 #else
@@ -106,14 +106,16 @@ const char * lookup_self_path()
 #if defined(_OS_WINDOWS_)
     if (!GetModuleFileNameA(GetModuleHandle(NULL), self_path, PATH_MAX)) {
         fprintf(stderr, "ERROR: GetModuleFileName() failed\n");
-        exit(1);
+        strcpy(self_path, "<unknown>");
+        return self_path;
     }
 #else
     // On all other platforms, use dladdr()
     Dl_info info;
     if (!dladdr(lookup_self_symbol("lbt_forward"), &info)) {
         fprintf(stderr, "ERROR: Unable to dladdr(\"lbt_forward\"): %s\n", dlerror());
-        exit(1);
+        strcpy(self_path, "<unknown>");
+        return self_path;
     }
     strcpy(self_path, info.dli_fname);
 #endif

src/libblastrampoline.c

@@ -274,8 +274,8 @@ LBT_DLLEXPORT int32_t lbt_forward(const char * libname, int32_t clear, int32_t v
                     printf(" -> CBLAS not found\n");
                     break;
                 default:
-                    printf(" -> ERROR: CBLAS DETECTION FAILED UNEXPECTEDLY\n");
-                    exit(1);
+                    printf(" -> ERROR: Impossible CBLAS detection result: %d\n", cblas);
+                    cblas = LBT_CBLAS_UNKNOWN;
                     break;
             }
         }

src/libblastrampoline_internal.h

@@ -92,7 +92,7 @@ int32_t autodetect_cblas_divergence(void * handle, const char * suffix);
 #endif
 
 // Functions in deepbindless_surrogates.c
-void push_fake_lsame();
-void pop_fake_lsame();
+uint8_t push_fake_lsame();
+uint8_t pop_fake_lsame();
 int fake_lsame(char * ca, char * cb);
 extern uint8_t use_deepbind;