Fix a shader compilation bug affecting release builds

glShaderSource was being called with arguments which signify
null-terminated strings when some sources were not null-terminated.

src/demo.c

@@ -33,8 +33,6 @@ typedef struct {
 } fbo_t;
 
 typedef struct {
-    int width;
-    int height;
     double aspect_ratio;
     int x0;
     int y0;
@@ -99,7 +97,8 @@ static int replace_program(program_t *old, program_t new) {
 void demo_reload(demo_t *demo) {
     demo->programs_ok = 1;
 
-    shader_t vertex_shader = compile_shader(vertex_shader_src, "vert", NULL, 0);
+    shader_t vertex_shader = compile_shader(
+        vertex_shader_src, strlen(vertex_shader_src), "vert", NULL, 0);
     shader_t fragment_shader =
         compile_shader_file("shaders/shader.frag", NULL, 0);
 
@@ -185,8 +184,6 @@ demo_t *demo_init(int width, int height) {
         return NULL;
     }
 
-    demo->width = width;
-    demo->height = height;
     demo->aspect_ratio = (double)width / (double)height;
     demo_resize(demo, width, height);
 
@@ -391,13 +388,12 @@ void demo_render(demo_t *demo, struct sync_device *rocket, double rocket_row) {
     // Animate shader reload to show feedback in debug builds
     float a = fmin((SDL_GetTicks64() - demo->reload_time) / 100.f, 1.);
     const GLint x0 = demo->x0 * a, x1 = demo->x1 * a, y0 = demo->y0 * a,
-                y1 = demo->y1 * a, w = demo->width, h = demo->height;
+                y1 = demo->y1 * a;
 #else
-    const GLint x0 = demo->x0, x1 = demo->x1, y0 = demo->y0, y1 = demo->y1,
-                w = demo->width, h = demo->height;
+    const GLint x0 = demo->x0, x1 = demo->x1, y0 = demo->y0, y1 = demo->y1;
 #endif
-    glBlitFramebuffer(0, 0, w, h, x0, y0, x1, y1, GL_COLOR_BUFFER_BIT,
-                      GL_LINEAR);
+    glBlitFramebuffer(0, 0, demo->fbs[2].width, demo->fbs[2].height, x0, y0, x1,
+                      y1, GL_COLOR_BUFFER_BIT, GL_LINEAR);
 
     // Switch fb to keep render results in memory for feedback effects
     demo->firstpass_fb_idx = alt_fb_idx;

src/shader.c

@@ -25,16 +25,14 @@ static size_t read_file(const char *filename, char **dst) {
         goto cleanup;
     }
 
-    *dst = (char *)malloc(len + 1);
+    *dst = (char *)malloc(len);
     fseek(file, 0, SEEK_SET);
 
     size_t read = fread(*dst, sizeof(char), len, file);
     fclose(file);
     if (read != len)
         goto cleanup;
 
-    (*dst)[len] = '\0';
-
     return len;
 
 cleanup:
@@ -71,9 +69,21 @@ static GLenum type_to_enum(const char *shader_type) {
     return GL_INVALID_ENUM;
 }
 
-shader_t compile_shader(const char *shader_src, const char *shader_type,
-                        const shader_define_t *defines, size_t n_defs) {
+shader_t compile_shader(const char *shader_src, size_t shader_src_len,
+                        const char *shader_type, const shader_define_t *defines,
+                        size_t n_defs) {
     static const char *src[MAX_SRC_FRAGMENTS];
+    static GLint src_lens[MAX_SRC_FRAGMENTS];
+
+    // Set src_lens to all 1-bits because that will cause them to be negative.
+    //
+    // glShaderSource documentation:
+    //
+    // Each element in the length array may contain the length of the
+    // corresponding string (the null character is not counted as part
+    // of the string length) or a value less than 0 to indicate that
+    // the string is null terminated.
+    memset(src_lens, ~0, MAX_SRC_FRAGMENTS * sizeof(GLint));
 
     shader_t ret = {0};
     ret.uniforms = parse_uniforms(shader_src, &ret.uniform_count);
@@ -90,9 +100,10 @@ shader_t compile_shader(const char *shader_src, const char *shader_type,
             src[i++] = "\n";
         }
     }
+    src_lens[i] = shader_src_len;
     src[i++] = shader_src;
 
-    glShaderSource(ret.handle, i, src, NULL);
+    glShaderSource(ret.handle, i, src, src_lens);
     glCompileShader(ret.handle);
 
     GLint status;
@@ -115,8 +126,8 @@ shader_t compile_shader(const char *shader_src, const char *shader_type,
 shader_t compile_shader_file(const char *filename,
                              const shader_define_t *defines, size_t n_defs) {
     char *shader_src = NULL;
-
-    if (read_file(filename, &shader_src) == 0) {
+    size_t shader_src_len = read_file(filename, &shader_src);
+    if (shader_src_len == 0) {
         return (shader_t){0};
     }
 
@@ -128,7 +139,8 @@ shader_t compile_shader_file(const char *filename,
         }
     } while (ret);
 
-    shader_t shader = compile_shader(shader_src, shader_type, defines, n_defs);
+    shader_t shader = compile_shader(shader_src, shader_src_len, shader_type,
+                                     defines, n_defs);
 #ifdef DEBUG
     free(shader_src);
 #endif

src/shader.h

@@ -22,8 +22,9 @@ typedef struct {
     size_t uniform_count;
 } program_t;
 
-shader_t compile_shader(const char *shader_src, const char *shader_type,
-                        const shader_define_t *defines, size_t n_defs);
+shader_t compile_shader(const char *shader_src, size_t shader_src_len,
+                        const char *shader_type, const shader_define_t *defines,
+                        size_t n_defs);
 shader_t compile_shader_file(const char *filename,
                              const shader_define_t *defines, size_t n_defs);
 program_t link_program(shader_t *shaders, size_t count);