cleanup

Signed-off-by: Andrea Terzolo <andreaterzolo3@gmail.com>
Co-authored-by: Mauro Ezequiel Moltrasio <mmoltras@redhat.com>

userspace/libpman/src/configuration.c

@@ -171,14 +171,92 @@ int pman_get_required_buffers()
 
 static char byte_array[] = "BPF_TRACE_RAW_TP";
 
-bool check_BPF_TRACE_RAW_TP(void)
+bool check_location(const char* path)
+{
+	bool res = false;
+
+	// On success `faccessat` returns 0.
+	if(faccessat(0, path, R_OK, AT_EACCESS) != 0)
+	{
+		return false;
+	}
+
+	char *file_content = NULL;
+	FILE *f = fopen(path, "r");
+	if(!f)
+	{
+		return false;
+	}
+
+	// Seek to the end of file
+	if(fseek(f, 0, SEEK_END))
+	{
+		goto cleanup;
+	}
+
+	// Return the dimension of the file
+	long sz = ftell(f);
+	if (sz < 0)
+	{
+		goto cleanup;
+	}
+
+	// Seek again to the beginning of the file
+	if(fseek(f, 0, SEEK_SET))
+	{
+		goto cleanup;
+	}
+
+	// pre-alloc memory to read all of BTF data 
+	file_content = malloc(sz);
+	if (!file_content)
+	{
+		goto cleanup;
+	}
+
+	// read all of BTF data
+	if(fread(file_content, 1, sz, f) < sz)
+	{
+		goto cleanup;
+	}
+
+	// Search 'BPF_TRACE_RAW_TP' byte array
+	int z = 0;
+	for(int j = 0; j< sz; j++)
+	{
+		if(file_content[j] == byte_array[z])
+		{
+			z++;
+			if(z == sizeof(byte_array) / sizeof(*byte_array))
+			{
+				res = true;
+				break;
+			}
+		}
+		else
+		{
+			z = 0;
+		}
+	}
+
+cleanup:
+	if(f)
+	{
+		fclose(f);
+	}
+	if(file_content)
+	{
+		free(file_content);
+	}
+	return res;
+}
+
+bool probe_BPF_TRACE_RAW_TP_type(void)
 {
 	// These locations are taken from libbpf library:
 	// https://elixir.bootlin.com/linux/latest/source/tools/lib/bpf/btf.c#L4767
 	const char *locations[] = {
-		/* try canonical vmlinux BTF through sysfs first */
 		"/sys/kernel/btf/vmlinux",
-		/* fall back to trying to find vmlinux on disk otherwise */
 		"/boot/vmlinux-%1$s",
 		"/lib/modules/%1$s/vmlinux-%1$s",
 		"/lib/modules/%1$s/build/vmlinux",
@@ -187,97 +265,31 @@ bool check_BPF_TRACE_RAW_TP(void)
 		"/usr/lib/debug/boot/vmlinux-%1$s.debug",
 		"/usr/lib/debug/lib/modules/%1$s/vmlinux",
 	};
-	char path[PATH_MAX + 1];
-	struct utsname buf;
-	char *data = NULL;
-	FILE *f = NULL;
-	uname(&buf);
 
-	for (int i = 0; i < sizeof(locations) / sizeof(*locations); i++)
+	// Try canonical `vmlinux` BTF through `sysfs` first.
+	if(check_location(locations[0]))
 	{
-		snprintf(path, PATH_MAX, locations[i], buf.release);
-
-		// On success `faccessat` returns 0.
-		if(faccessat(0, path, R_OK, AT_EACCESS) != 0)
-		{
-			// The file doesn't exist, loop on the next one.
-			continue;
-		}
-
-		f = fopen(path, "r");
-		if(!f)
-		{
-			goto loop_again;
-		}
-
-		// Seek to the end of file
-		if(fseek(f, 0, SEEK_END))
-		{
-			goto loop_again;
-		}
-
-		// Return the dimension of the file
-		long sz = ftell(f);
-		if (sz < 0)
-		{
-			goto loop_again;
-		}
-
-		// Seek again to the beginning of the file
-		if(fseek(f, 0, SEEK_SET))
-		{
-			goto loop_again;
-		}
-
-		// pre-alloc memory to read all of BTF data 
-		data = malloc(sz);
-		if (!data)
-		{
-			goto loop_again;
-		}
+		return true;
+	}
 
-		// read all of BTF data
-		if(fread(data, 1, sz, f) < sz)
-		{
-			goto loop_again;
-		}
+	// Fall back to trying to find `vmlinux` on disk otherwise
+	struct utsname buf = {};
+	if(uname(&buf) == -1)
+	{
+		return false;
+	}
 
-		// Search 'BPF_TRACE_RAW_TP' byte array
-		int z = 0;
-		for(int j = 0; j< sz; j++)
-		{
-			if(data[j] == byte_array[z])
-			{
-				z++;
-				if(z == sizeof(byte_array) / sizeof(*byte_array))
-				{
-					fclose(f);
-					free(data);
-					return true;
-				}
-			}
-			else
-			{
-				z = 0;
-			}
-		}
-loop_again:
+	char path[PATH_MAX + 1];
 
-		if(f)
-		{
-			fclose(f);
-			f = NULL;
-		}
-		if(data)
+	// Skip vmlinux since we already tested it.
+	for (int i = 1; i < sizeof(locations) / sizeof(*locations); i++)
+	{
+		snprintf(path, PATH_MAX, locations[i], buf.release);
+		if(check_location(path))
 		{
-			free(data);
-			data = NULL;
+			return true;
 		}
 	}
-
-	// Clear the errno for `pman_print_error`
-	errno = 0;
-	pman_print_error("prog 'BPF_TRACE_RAW_TP' is not supported");
 	return false;
 }
 
@@ -302,7 +314,14 @@ bool pman_check_support()
 		// to check for the `BPF_TRACE_RAW_TP` one. If `BPF_TRACE_FENTRY` is defined we are
 		// sure `BPF_TRACE_RAW_TP` is defined as well, in all other cases, we need to search
 		// for it in the `vmlinux` file.
-		return check_BPF_TRACE_RAW_TP();
+		res = probe_BPF_TRACE_RAW_TP_type();
+		if(!res)
+		{
+			// Clear the errno for `pman_print_error`
+			errno = 0;
+			pman_print_error("prog 'BPF_TRACE_RAW_TP' is not supported");
+			return res;
+		}
 	}
 
 	/* Probe result depends on the success of map creation, no additional