Worked through ex20

Makefile

@@ -1,4 +1,4 @@
-CFLAGS=-Wall -g
+CFLAGS=-Wall -g -DNDEBUG
 
 EXERCISES = $(patsubst %.c,%,$(shell ls ex*.c | grep -v ex19))
 

dbg.h

@@ -0,0 +1,40 @@
+#ifndef __dbg_h__
+#define __dbg_h__
+
+#include <stdio.h>
+#include <errno.h>
+#include <string.h>
+
+#ifdef NDEBUG
+#define debug(M, ...)
+#else
+#define debug(M, ...) \
+    fprintf(stderr, "DEBUG %s:%d:[%s]: " M "\n", \
+            __FILE__, __LINE__, __FUNCTION__, ##__VA_ARGS__)
+#endif
+
+#define clean_errno() (errno == 0 ? "None" : strerror(errno))
+
+#define log_err(M, ...) \
+    fprintf(stderr, "[ERROR] (%s:%d:[%s]: errno: %s) " M "\n", \
+            __FILE__, __LINE__, __FUNCTION__, clean_errno(), ##__VA_ARGS__)
+
+#define log_warn(M, ...) \
+    fprintf(stderr, "[WARN] (%s:%d:[%s]: errno: %s) " M "\n", \
+            __FILE__, __LINE__, __FUNCTION__, clean_errno(), ##__VA_ARGS__)
+
+#define log_info(M, ...) \
+    fprintf(stderr, "[INFO] (%s:%d:[%s]: errno: %s) " M "\n", \
+            __FILE__, __LINE__, __FUNCTION__, clean_errno(), ##__VA_ARGS__)
+
+#define check(A, M, ...) \
+    if(!(A)) { log_err(M, ##__VA_ARGS__); errno=0; goto error; }
+
+#define sentinel(M, ...) { log_err(M, ##__VA_ARGS__); errno=0; goto error; }
+
+#define check_mem(A) check((A), "Out of memory.")
+
+#define check_debug(A, M, ...) \
+    if(!(A)) { debug(M,  ##__VA_ARGS__); errno=0; goto error; }
+
+#endif

ex19.mk

@@ -1,4 +1,4 @@
-CFLAGS=-Wall -g
+CFLAGS := -Wall -g
 
 all: ex19
 

ex20.c

@@ -0,0 +1,125 @@
+#include "dbg.h"
+#include <stdlib.h>
+#include <stdio.h>
+
+
+void test_debug()
+{
+    // notice you don't need the \n
+    debug("I have Brown Hair.");
+
+    // passing in arguments like printf
+    debug("I am %d years old.", 37);
+}
+
+
+void test_log_err()
+{
+    log_err("I believe everything is broken.");
+    log_err("There are %d problems in %s.", 0, "space");
+}
+
+
+void test_log_warn()
+{
+    log_warn("You can safely ignore this.");
+    log_warn("Maybe consider looking at: %s", "/etc/passwd");
+}
+
+
+void test_log_info()
+{
+    log_info("Well I did something mundane.");
+    log_info("It happened %f times today.", 1.3f);
+}
+
+
+int test_check(char *file_name)
+{
+    FILE *input = NULL;
+    char *block = NULL;
+
+    block = malloc(100);
+    check_mem(block); // should work
+
+    input = fopen(file_name, "r");
+    check(input, "Failed to open %s.", file_name);
+
+    free(block);
+    fclose(input);
+    return 0;
+
+error:
+    if(block) free(block);
+    if(input) fclose(input);
+    return -1;
+}
+
+
+int test_sentinel(int code)
+{
+    char *temp = malloc(100);
+    check_mem(temp);
+
+    switch(code) {
+        case 1:
+            log_info("It worked.");
+            break;
+        default:
+            sentinel("I shouldn't run.");
+    }
+
+    free(temp);
+    return 0;
+
+error:
+    if(temp) free(temp);
+    return -1;
+}
+
+
+int test_check_mem()
+{
+    char *test = NULL;
+    check_mem(test);
+
+    free(test);
+    return 1;
+
+error:
+    return -1;
+}
+
+
+int test_check_debug()
+{
+    int i = 0;
+    check_debug(i != 0, "Oops, I was 0.");
+
+    return 0;
+error:
+    return -1;
+}
+
+
+int main(int argc, char *argv[])
+{
+    check(argc == 2, "Need an argument.");
+
+    test_debug();
+    test_log_err();
+    test_log_warn();
+    test_log_info();
+
+    check(test_check("ex20.c") == 0, "failed with ex20.c");
+    check(test_check(argv[1]) == -1, "failed with argv");
+    check(test_sentinel(1) == 0, "test_sentinel failed.");
+    check(test_sentinel(100) == -1, "test_sentinel failed.");
+    check(test_check_mem() == -1, "test_check_mem failed.");
+    check(test_check_debug() == -1, "test_check_debug failed.");
+
+    return 0;
+
+error:
+    return 1;
+}