[PATCH] syscall: utility overhaul

[kvik@a-b.xyz]

Following is a list of functional changes:

* The -o flag outputs the entire buffer to the length returned
  by the syscall, or, in case of fd2path(2) and errstr(2), to '\0'.
* The -x flag is removed; the above makes it possible to pipe
  into xd(1) to get the same result.
* The -s flag uses dirfmt(2) to format the stat message, instead
  of trying to imitate ls(1).
* Stderr reports are normalized and made easier to parse.

The code also suffered a number of stylistic changes.

diff -r d947a4c5d7fa sys/man/1/syscall
--- a/sys/man/1/syscall	Thu Sep 03 20:07:44 2020 -0700
+++ b/sys/man/1/syscall	Sat Sep 19 15:04:17 2020 +0200
@@ -4,7 +4,7 @@
 .SH SYNOPSIS
 .B syscall
 [
-.B -osx
+.B -os
 ]
 .I entry
 [
@@ -15,39 +15,44 @@
 invokes the system call
 .I entry
 with the given arguments.
-(Some functions, such as
-.I write
+The return value is printed.
+If an error occured, the error string is also printed.
+.PP
+For convenience,
+.IR write (2)
 and
-.IR read (2),
-although not strictly system calls, are valid
-.IR entries .)
-It prints the return value and the error string, if there was an error.
-An argument is either an integer constant as in C (its value is passed),
-a string (its address is passed),
-or the literal
+.IR read (2)
+are included in
+.IR entries ,
+even though they are not strictly syscalls.
+.PP
+.I Syscall
+arguments are integer constants, strings, or the literal
+.BR buf .
+The literal
 .B buf
-(a pointer to a 1MB buffer is passed).
+refers to a writable 1 megabyte buffer.
+Strings and 
+.B buf
+are passed as pointers.
+Integers are passed as values.
 .PP
-If
+The
 .B -o
-is given, the contents of the 1MB buffer are printed as a zero-terminated string
-after the system call is done.
+option prints contents of the 1MB buffer.
+For
+.IR errstr (2)
+and
+.IR fd2path (2),
+the buffer is treated as a 0-terminated string.
+For other calls, the number of bytes printed is
+determined by the system call's return value.
+.PP
 The
-.B -x
-and
 .B -s
-options are similar, but
-.B -x
-formats the data as hexadecimal bytes, while
-.B -s
-interprets the data as a
+option is similar, but interprets the data as a
 .IR stat (5)
-message and formats it similar to the style of
-.B ls
-.B -lqm
-(see
-.IR ls (1)),
-with extra detail about the modify and access times.
+message and formats it to standard output.
 .SH EXAMPLES
 Write a string to standard output:
 .IP
diff -r d947a4c5d7fa sys/src/cmd/syscall/mkfile
--- a/sys/src/cmd/syscall/mkfile	Thu Sep 03 20:07:44 2020 -0700
+++ b/sys/src/cmd/syscall/mkfile	Sat Sep 19 15:04:17 2020 +0200
@@ -1,5 +1,4 @@
 </$objtype/mkfile
-CFLAGS=-I/sys/src/libc/9syscall $CFLAGS
 
 TARG=syscall
 OFILES=syscall.$O\
@@ -18,12 +17,24 @@
 SYSCALL=/sys/src/libc/9syscall/sys.h
 
 tab.h:	$SYSCALL
-	sed '/#define._X[0-9_]/d;
-		/#define.NSYSCALL/d;
-		s/#define.([A-Z0-9_][A-Z0-9_]*).*/	"\1",	(int(*)(...))\1,/' $SYSCALL |
-		tr A-Z a-z > tab.h
-	echo '	"read",	(int(*)(...))read,' >> tab.h
-	echo '	"write",	(int(*)(...))write,' >> tab.h
+	awk '
+	BEGIN{ print "enum{" }
+	{ printf "%s, ", $2 }
+	END{
+		print "READ, WRITE, NTAB"
+		print "};"
+	}' <$SYSCALL >$target 
+	awk '
+	BEGIN{ print "struct Call tab[] = {" }
+	{ printf "[%s] \"%s\", (int(*)(...))%s,\n",
+		$2, tolower($2), tolower($2)
+	}
+	END{
+		print "[READ] \"read\", (int(*)(...))read,"
+		print "[WRITE] \"write\", (int(*)(...))write,"
+		print "[NTAB] nil, 0"
+		print "};"
+	}' <$SYSCALL >>$target
 
 clean:V:
 	rm -f *.[$OS] [$OS].out $TARG $HFILES
diff -r d947a4c5d7fa sys/src/cmd/syscall/syscall.c
--- a/sys/src/cmd/syscall/syscall.c	Thu Sep 03 20:07:44 2020 -0700
+++ b/sys/src/cmd/syscall/syscall.c	Sat Sep 19 15:04:17 2020 +0200
@@ -1,10 +1,9 @@
 #include <u.h>
 #include <libc.h>
-#include <sys.h>
 #include <fcall.h>
 
 char	buf[1048576];
-#define	NARG	5
+enum{ NARG = 5 };
 uintptr	arg[NARG];
 
 /* system calls not defined in libc.h */
@@ -28,65 +27,55 @@
 int	_wait(void*);
 int	_nsec(vlong*);
 
-struct{
+struct Call{
 	char	*name;
 	int	(*func)(...);
-}tab[]={
+};
 #include "tab.h"
-	0,		0
-};
 
-uintptr parse(char *);
-void catch(void*, char*);
-
-char*
-xctime(ulong t)
+void
+usage(void)
 {
-	char *buf, *s;
-
-	s = ctime(t);
-	s[strlen(s)-1] = '\0';	/* remove newline */
-	buf = malloc(512);
-	if(buf == nil)
-		sysfatal("can't malloc: %r");
-	snprint(buf, 512, "%s (%lud)", s, t);
-	return buf;
+	fprint(2, "usage: %s [-os] entry [arg ...]\n", argv0);
+	exits("usage");
 }
 
+uintptr
+parse(char *s)
+{
+	char *t;
+	uintptr l;
 
-char*
-lstime(long l)
+	if(strncmp(s, "buf", 3) == 0)
+		return (uintptr)buf;
+	
+	l = strtoull(s, &t, 0);
+	if(t > s && *t == 0)
+		return l;
+
+	return (uintptr)s; 
+}
+
+void
+catch(void *, char *msg)
 {
-	static char buf[32];
-	char *t;
-	long clk;
-
-	clk = time(0);
-	t = ctime(l);
-	/* 6 months in the past or a day in the future */
-	if(l<clk-180L*24*60*60 || clk+24L*60*60<l){
-		memmove(buf, t+4, 7);		/* month and day */
-		memmove(buf+7, t+23, 5);		/* year */
-	}else
-		memmove(buf, t+4, 12);		/* skip day of week */
-	buf[12] = 0;
-	return buf;
+	fprint(2, "syscall: received note: %s\n", msg);
+	noted(NDFLT);
 }
 
 void
 main(int argc, char *argv[])
 {
-	int i, j, c;
-	int oflag, xflag, sflag;
-	vlong r;
+	int i;
+	int oflag, sflag;
+	vlong r, nbuf;
 	Dir d;
 	char strs[1024];
-	char ebuf[1024];
+	char ebuf[ERRMAX];
 
-	fmtinstall('M', dirmodefmt);
+	fmtinstall('D', dirfmt);
 
 	oflag = 0;
-	xflag = 0;
 	sflag = 0;
 	ARGBEGIN{
 	case 'o':
@@ -95,97 +84,57 @@
 	case 's':
 		sflag++;
 		break;
-	case 'x':
-		xflag++;
+	default:
+		usage();
+	}ARGEND
+	if(argc < 1 || argc > 1+NARG)
+		usage();
+
+	for(i = 1; i < argc; i++)
+		arg[i-1] = parse(argv[i]);
+	for(i = 0; tab[i].name; i++)
+		if(strcmp(tab[i].name, argv[0]) == 0)
+			break;
+	if(i == NTAB){
+		fprint(2, "syscall: %s not known\n", argv[0]);
+		exits("unknown");
+	}
+	notify(catch);
+	/* special case for seek, pread, pwrite; vlongs are problematic */
+	switch(i){
+	default:
+		r = (*tab[i].func)(arg[0], arg[1], arg[2], arg[3], arg[4]);
 		break;
-	default:
-		goto Usage;
-	}ARGEND
-	if(argc<1 || argc>1+NARG){
-    Usage:
-		fprint(2, "usage: syscall [-ox] entry [args; buf==1MB buffer]\n");
-		fprint(2, "\tsyscall write 1 hello 5\n");
-		fprint(2, "\tsyscall -o errstr buf 1024\n");
-		fprint(2, "\tsyscall -[xs] stat file buf 1024\n");
-		exits("usage");
+	case SEEK:
+		r = seek(arg[0], strtoll(argv[2], 0, 0), arg[2]);
+		break;
+	case PREAD:
+		r = pread(arg[0], (void*)arg[1], arg[2], strtoll(argv[4], 0, 0));
+		break;
+	case PWRITE:
+		r = pwrite(arg[0], (void*)arg[1], arg[2], strtoll(argv[4], 0, 0));
+		break;
 	}
-	for(i=1; i<argc; i++)
-		arg[i-1] = parse(argv[i]);
-	notify(catch);
-	for(i=0; tab[i].name; i++)
-		if(strcmp(tab[i].name, argv[0])==0){
-			/* special case for seek, pread, pwrite; vlongs are problematic */
-			if(strcmp(argv[0], "seek") == 0)
-				r=seek(arg[0], strtoll(argv[2], 0, 0), arg[2]);
-			else if(strcmp(argv[0], "pread") == 0)
-				r=pread(arg[0], (void*)arg[1], arg[2], strtoll(argv[4], 0, 0));
-			else if(strcmp(argv[0], "pwrite") == 0)
-				r=pwrite(arg[0], (void*)arg[1], arg[2], strtoll(argv[4], 0, 0));
-			else
-				r=(*tab[i].func)(arg[0], arg[1], arg[2], arg[3], arg[4]);
-			if(r == -1){
-				errstr(ebuf, sizeof ebuf);
-				fprint(2, "syscall: return %lld, error:%s\n", r, ebuf);
-			}else{
-				ebuf[0] = 0;
-				fprint(2, "syscall: return %lld, no error\n", r);
-			}
-			if(oflag)
-				print("%s\n", buf);
-			if(xflag){
-				for(j=0; j<r; j++){
-					if(j%16 == 0)
-						print("%.4x\t", j);
-					c = buf[j]&0xFF;
-					if('!'<=c && c<='~')
-						print(" %c ", c);
-					else
-						print("%.2ux ", c);
-					if(j%16 == 15)
-						print("\n");
-				}
-				print("\n");
-			}
-			if(sflag && r > 0){
-				r = convM2D((uchar*)buf, r, &d, strs);
-				if(r <= BIT16SZ)
-					print("short stat message\n");
-				else{
-					print("[%s] ", d.muid);
-					print("(%.16llux %lud %.2ux) ", d.qid.path, d.qid.vers, d.qid.type);
-					print("%M (%luo) ", d.mode, d.mode);
-					print("%c %d ", d.type, d.dev);
-					print("%s %s ", d.uid, d.gid);
-					print("%lld ", d.length);
-					print("%s ", lstime(d.mtime));
-					print("%s\n", d.name);
-					print("\tmtime: %s\n\tatime: %s\n", xctime(d.mtime), xctime(d.atime));
-				}
-			}
-			exits(ebuf);
+	if(r == -1){
+		errstr(ebuf, sizeof ebuf);
+		fprint(2, "syscall: return: %lld error: %s\n", r, ebuf);
+		exits(ebuf);
+	}
+	fprint(2, "syscall: return: %lld\n", r);
+	if(oflag){
+		nbuf = r;
+		switch(i){
+		case _ERRSTR: case ERRSTR: case FD2PATH:
+			nbuf = strlen(buf);
 		}
-	fprint(2, "syscall: %s not known\n", argv[0]);
-	exits("unknown");
+		if(write(1, buf, nbuf) != nbuf)
+			sysfatal("write: %r");
+	}else if(sflag){
+		r = convM2D((uchar*)buf, r, &d, strs);
+		if(r <= BIT16SZ)
+			print("short stat message\n");
+		else
+			print("%D\n", &d);
+	}
+	exits(nil);
 }
-
-uintptr
-parse(char *s)
-{
-	char *t;
-	uintptr l;
-
-	if(strcmp(s, "buf") == 0)
-		return (uintptr)buf;
-	
-	l = strtoull(s, &t, 0);
-	if(t>s && *t==0)
-		return l;
-	return (uintptr)s; 
-}
-
-void
-catch(void *, char *msg)
-{
-	fprint(2, "syscall: received note='%s'\n", msg);
-	noted(NDFLT);
-}