Added better error handling

src/cat.c

@@ -2,6 +2,7 @@
 /* A way slimmer version of cat without the GNU bloat features that I have never used nor needed */
 #include <stdio.h> //fprintf, perror
 #include <stdlib.h> //exit
+#include <err.h> //err, errx
 #include <unistd.h> //read, write, close
 #include <sys/types.h> //stat
 #include <sys/stat.h> //stat
@@ -13,36 +14,28 @@
 #define BUFF_SIZE 10000 //a larger buffer trades memory for speed
 #define MAX_SENDFILE_LINUX 2147479552 //max file size for sendfile in Linux
 
-void throw_error(const char* extra_msg, const int exit_code){
-/* function to writes the program name, optionally extra info, then the error to stderr */
-	if(extra_msg != NULL) fprintf(stderr, "%s: %s: ", NAME, extra_msg);
-	else fprintf(stderr, "%s: ", NAME);
-	perror("");
-	if(exit_code) exit(exit_code); //allows non-fatal errors to keep going
-}
 void cat(const int fd, const char no_buf, size_t size){
 /* reads from the file descriptor into buf, until zero bytes are read  */
 	//tries sendfile if available (since it is faster, if not, do sys read & write)
 	if(fd == STDIN_FILENO || size > MAX_SENDFILE_LINUX || sendfile(STDOUT_FILENO, fd, 0, size) != size){
 		size_t r = 0;
 		if(no_buf) size = 1;
 		void *buf = (void*)malloc(size);
-		if(buf == NULL) throw_error("Buffer Allocation", 4);
+		if(buf == NULL) err(EXIT_FAILURE, "while allocating buf in cat()");
 		while((r=read(fd, buf, size)) > 0)
-			if(write(STDOUT_FILENO, buf, r) != r) throw_error(NULL, 3); //if writing stops for some reason
-		if(r == -1) throw_error(NULL, 1); //if read(2) throws an error
+			if(write(STDOUT_FILENO, buf, r) != r) err(EXIT_FAILURE, "while writing to fd in cat(). %ld bytes were written", r); //if writing stops for some reason
+		if(r == -1) err(EXIT_FAILURE, "while reading fd in cat()."); //if read(2) throws an error
 		free(buf);
-	} //else 
-	//	throw_error("Unable to cat file.", 1);
+	} 
 }
 void get_file(const char* file_name, const char no_buf){
 /* tries to open the user's file, then calls cat() with its file pointer */
 	if(file_name[0] == '-' && file_name[1] == '\0'){ cat(STDIN_FILENO, no_buf, BUFF_SIZE); return;}
 	struct stat buffer;
 	int fd = -1, status = stat(file_name, &buffer);
-	if(status != 0) throw_error(file_name, 1);
+	if(status != 0) err(EXIT_FAILURE, "while checking file '%s' in get_file()", file_name);
 	fd = open(file_name, O_RDONLY);
-	if(fd == -1) throw_error(file_name, 1);
+	if(fd == -1) err(EXIT_FAILURE, "while opening file '%s' in get_file()", file_name); 
 	cat(fd, no_buf, buffer.st_size);
 	close(fd);
 }
@@ -55,7 +48,7 @@ int main(int argc, char *argv[]){
 		else if(argv[i][0] == '-' && argv[i][1] != '\0'){ //if its a command line arg
 			if(argv[i][1] == 'h') { puts(HELP); return 0; }
 			else if(argv[i][1] == 'u') no_buf = 1; //required by POSIX, turns off buffered output
-			else { fprintf(stderr, "%s: unknown command line arg '%s'\n", NAME, argv[i]); return 2;}
+			else errx(EXIT_FAILURE, "while reading command line arg %ld in main(): unknown command line arg '%s'\n", i, argv[i]);
 		} else {
 			for( ; i < argc; i++) get_file(argv[i], no_buf); //step through each arg as if it's a file, even if its a -
 		}