opengl

commit dd9042cea8550135e40dc7e1dd9b90a63096e89e
parent 59fbab53ee580386a1601fea22d01f39ef861113
Author: Matsuda Kenji <info@mtkn.jp>
Date:   Sun, 25 Jun 2023 18:43:05 +0900

allocate memory dynamically

Diffstat:
M
main.c
 | 
36
++++++++++++++++++++++++++++++++----

1 file changed, 32 insertions(+), 4 deletions(-)
diff --git a/main.c b/main.c
@@ -36,19 +36,47 @@ readfile(const char *file)
 		return NULL;
 	}
 	
-	size_t bufsize = 1024;
+	size_t bufsize = 128;
+	size_t bytesRead = 0;
 	char *c;
 	c = (char *)malloc(bufsize);
+	if (c == NULL) {
+		snprintf(errstr, sizeof(errstr),
+			"allocate memory: errno = %d", errno);
+		return NULL;
+	}	
 	
-	size_t read = fread(c, sizeof(c[0]), bufsize, f);
-	if (read == sizeof(c)) {
+	for (;;) {
+		size_t read = fread(&c[bytesRead], sizeof(c[0]),
+			bufsize-bytesRead, f);
+		bytesRead += read;
+		if (read < bufsize - bytesRead) {
+			break;
+		}
+		bufsize *= 2; // TODO: check overflow.
+		char* newc = (char *)realloc(c, bufsize);
+		if (newc == NULL) {
+			snprintf(errstr, sizeof(errstr),
+				"allocate memory: errno = %d", errno);
+			free(c);
+			return NULL;
+		}
+		c = newc;
+	}
+	if (!feof(f) || ferror(f)) {
 		snprintf(errstr, sizeof(errstr),
-			"read file: file too big: %s", file);
+			"read from file %s: errno = %d", file, errno);
+		free(c);
 		return NULL;
 	}
+	
+	c[bytesRead] = '\0';	
 	return c;
 }
 
+// ShaderInit create Shader struct with vertexShader specified by vs and
+// fragmentShader specified by fs. vs and fs are path names to the shader
+// files. It returns the pointer to the resulting struct.
 Shader *
 ShaderInit(const char *vs, const char *fs)
 {