some work on dj(1) for bonsai

Wip/dj/dj.c

@@ -0,0 +1,152 @@
+#include <errno.h> /* errno */
+#include <fcntl.h> /* open(2) */
+#include <stdio.h> /* fprintf(3), stderr */
+#include <stdlib.h> /* free(3), malloc(3), strtol(3), size_t */
+#include <sysexits.h> /* EX_OK, EX_USAGE */
+#include <unistd.h> /* close(2), getopt(3), optarg, optind, STDIN_FILENO,
+                       STDOUT_FILENO */
+
+#define ARGV0 (argv[0] == NULL ? "<no argv[0]>" : argv[0])
+
+static int /* on error returns -1, else returns non-negative */
+parse(char *s){
+	int r;
+
+	errno = 0;
+
+	return (*s == '\0' /* empty string */
+			|| *(s = (int)strtol(s, &s, 0)) != '\0' /* not fully processed */
+			|| errno != 0)
+		? -1
+		: r;
+}
+
+static int
+oserr(char *argv0, char *s){
+	fprintf(stderr, "%s: %s: %s\n", argv0, s, strerror(errno));
+	return EX_OSERR;
+}
+
+static int
+usage(char *argv0){
+	fprintf(stderr, "Usage: %s (-f) (-c [count]\n"
+		"\t(-i [input file]) (-a) (-b [input block size])"
+			" (-s [input offset])\n"
+		"\t(-o [output file]) (-A) (-B [output block size])"
+			" (-S [output offset])\n", ARGV0);
+	return EX_USAGE;
+}
+
+static char stdin_name = "<stdin>";
+static char stdout_name = "<stdout>";
+
+int main(int argc, char *argv[]){
+	struct Io{
+		char align;
+		char *fn;
+		int rec;
+		int prec;
+		int fd;
+		int seek;
+		int bs;
+		size_t bufuse;
+		char *buf;
+	} io[2]; /* { read, write } same as pipe(2) */
+	int c;
+	int count;
+	size_t i;
+	size_t p;
+	char noerror;
+
+	/* defaults */
+	count = 0;
+	noerror = 0;
+	io[0].align = io[1].align = 0;
+	io[0].bs = io[1].bs = 1024;
+	io[0].fd = STDIN_FILENO;
+	io[0].fn = stdin_name;
+	io[1].fd = STDOUT_FILENO;
+	io[1].fn = stdout_name;
+	io[0].seek = io[1].seek = 0;
+
+	if(argc > 0)
+		while((c = getopt(argc, argv, "aAc:i:b:fs:o:B:S:")) != -1)
+			if(c == 'i' || c == 'o'){ /* file arguments */
+				int t;
+
+				p = (c == 'o');
+				if(		(t = open(optarg,
+								c == 'i'
+								? O_RDONLY
+								: O_WRONLY | O_CREAT))
+							== -1)
+						|| (io[p].fd != STDIN_FILENO
+							&& io[p].fd != STDOUT_FILENO
+							&& fclose(io[p].f) == EOF){
+					return oserr(argv[0], optarg);
+				}else{
+					io[p].fd = t;
+					io[p].fn = optarg;
+				}
+			/* numeric arguments */
+			}else if(!((c == 'c' && (count = parse(optarg)) < 0)
+					|| (c == 'b' && (io[0].bs = parse(optarg)) < 0)
+					|| (c == 's' && (io[0].seek = parse(optarg)) < 0)
+					|| (c == 'B' && (io[1].bs = parse(optarg)) < 0)
+					|| (c == 'S' && (io[1].seek = parse(optarg)) < 0)))
+				return usage(argv[0]);
+			/* boolean arguments */
+			else if(c == 'a' || c == 'A')
+				io[c == 'A'].align = 1;
+			else if(c == 'f')
+				noerror = 1;
+
+	if(argc > optind)
+		return usage(argv[0]);
+
+	for(p = 0; p <= 1; ++p){
+		/* buffer alloc */
+		if((io[p].buf = malloc(io[p].bs * (sizeof io[p].buf))) == NULL){
+			fprintf(stderr, "%s: Failed to allocate %d bytes\n", ARGV0,
+				io[p].bs);
+			return EX_OSERR;
+		}else if(io[p].seek > 0){ /* seek */
+			if(io[p].fd == STDIN_FILENO){
+				do{	io[p].seek -= (io[p].bufuse
+						= read(io[p].fd, io[p].buf, io[p].ibs));
+					if(io[p].bufuse == 0)
+				while(io[p].seek > 0);
+
+			}
+				for(i = 0; i < io[p].seek; ++i)
+					(void)getc(io[p].f);
+			else if(io[p].f == stdout)
+				for(i = 0; i < io[p].seek; ++i)
+					putc('\0', io[p].f;
+			else if(fseek(io[p].f, io[p].seek, SEEK_SET) == -1)
+				return oserr(argv[0], io[p].fn);
+		}
+	}
+
+	io[0].prec = io[0].rec = io[1].prec = io[1].rec = 0;
+
+	do{	if(		(io[0].bufuse
+					= fread(io[0].buf, sizeof io[0].buf, io[0].bs, io[0].f))
+				< ibs){
+			if(feof(io[0].f) != 0)
+					count = 1;
+		}
+
+		while(io[0].bufuse > 0){
+		}
+
+	}while(count == 0 || --count > 0);
+
+	for(i = 0; i <= 1; ++i){
+		free(io[i].buf);
+		if(io[i].fd != STDIN_FILENO && io[i].fd != STDOUT_FILENO)
+			close(io[i].fd);
+	}
+
+	return EX_OK;
+}