nfs@notecnirp.Princeton.EDU (Norbert Schlenker) (01/09/90)
Here are three POSIX routines to go along with the new Minix (they'll work
with the old one too). A Makefile and a shell script that will turn them
into something approaching Tanenbaum standard format is included.
Included are:
sysconf() - an analogue of [f]pathconf() for non-file limits
execve() - rewritten version
ttyname() - rewritten version
Motivations for these routines:
sysconf() - missing from the 1.5.0 postings
execve() - I wanted to see if my fast string routines would help in
copying the environment and arguments - they did, but a
simple cleanup of the existing code did just as well
ttyname() - I want to get rid of <sys/dir.h> and Terrence Holm's version
used it - the new routine uses the POSIX *dir() functions
On my PC, execve() saves 30%-50% over the old routine (that doesn't mean
that the program you execute runs that much faster :-)). Ttyname() is about
60% faster (real and system time), due to buffering in the *dir() routines,
but uses more user time and more space.
For those who are willing, I'd like comments on the format of the files
included here. I haven't included with this posting the headers that turn
the _*.c files into working copies, but I think all the library routines
should make use of something like the __[A-Z]* macros (my standard whine).
Norbert
----------------------------- cut here --------------------------------
#!/bin/sh
echo x - Makefile
sed '/^X/s///' > Makefile << '/'
Xall:
X sh make_normal _execve.c execve.c
X sh make_normal _sysconf.c sysconf.c
X sh make_normal _ttyname.c ttyname.c
/
echo x - make_normal
sed '/^X/s///' > make_normal << '/'
Xsed '/#include <sys\/types.h>/d;
X /#include <errno.h>/d;
X /#include <limits.h>/d;
X /#include <minix\/callnr.h>/d;
X s/_ttyname/ttyname/;
X s/_execve/execve/;
X s/_sysconf/sysconf/;
X s/ (underware)//;
X s/_PRIVATE/PRIVATE/;
X s/_PUBLIC/PUBLIC/;
X s/_MM/MM/;
X s/_FS/FS/;
X s/__TTYNAME/ttyname/;
X s/__EXECVE/execve/;
X s/__SYSCONF/sysconf/;
X s/__FSTAT/fstat/;
X s/__STAT/stat/;
X s/__OPENDIR/opendir/;
X s/__READDIR/readdir/;
X s/__CLOSEDIR/closedir/;
X s/__CALL1/callm1/;
X s/__CALL3/callm3/' <$1 >$2
/
echo x - _execve.c
sed '/^X/s///' > _execve.c << '/'
X/* _execve.c POSIX 3.1.2 (underware)
X * int __EXECVE(char *path, char *argv[], char *envp[]);
X *
X * Executes a file.
X */
X
X#include <lib.h>
X#include <errno.h>
X#include <limits.h>
X#include <sys/types.h>
X#include <unistd.h>
X#include <minix/callnr.h>
X
X#define PTRSIZE sizeof(char *)
X
X_PRIVATE int count_pointers(p)
Xregister char **p;
X{
X register int n = 0;
X
X while (*p++ != (char *) NULL)
X ++n;
X return n;
X}
X
X_PUBLIC int __EXECVE(path, argv, envp)
Xchar *path; /* pointer to name of file to be executed */
Xchar *argv[]; /* pointer to argument array */
Xchar *envp[]; /* pointer to environment */
X{
X char stack[ARG_MAX];
X char **ap;
X register char *hp, *p;
X int nargs, nenvps, stackbytes;
X
X /* Count the argument pointers and environment pointers. */
X nargs = count_pointers(argv);
X nenvps = count_pointers(envp);
X
X /* Prepare to set up the initial stack. */
X hp = &stack[(nargs + nenvps + 3) * PTRSIZE];
X if (hp + nargs + nenvps >= &stack[ARG_MAX]) {
X errno = E2BIG;
X return -1;
X }
X ap = (char **) stack;
X *ap++ = (char *) nargs;
X
X /* Prepare the argument pointers and strings. */
X while (*argv != (char *) NULL) {
X *ap++ = (char *) (hp - stack);
X p = *argv++;
X while (*p) {
X *hp++ = *p++;
X if (hp >= &stack[ARG_MAX]) {
X errno = E2BIG;
X return -1;
X }
X }
X *hp++ = '\0';
X }
X *ap++ = (char *) NULL;
X
X /* Prepare the environment pointers and strings. */
X while (*envp != (char *) NULL) {
X *ap++ = (char *) (hp - stack);
X p = *envp++;
X while (*p) {
X *hp++ = *p++;
X if (hp >= &stack[ARG_MAX]) {
X errno = E2BIG;
X return -1;
X }
X }
X *hp++ = '\0';
X }
X *ap++ = (char *) NULL;
X stackbytes = (((int) (hp - stack) + PTRSIZE - 1) / PTRSIZE) * PTRSIZE;
X return __CALL1(_MM, EXEC, strlen(path) + 1, stackbytes, 0, path, stack, NULL);
X}
/
echo x - _sysconf.c
sed '/^X/s///' > _sysconf.c << '/'
X/* _sysconf.c POSIX 4.8.1 (underware)
X * long int __SYSCONF(int name);
X *
X * POSIX allows some of the values in <limits.h> to be increased at
X * run time. The sysconf() function allows such values to be checked
X * at run time. MINIX does not use this facility - the run time
X * limits are those given in <limits.h>.
X */
X
X#include <lib.h>
X#include <sys/types.h>
X#include <errno.h>
X#include <limits.h>
X#include <unistd.h>
X
X_PUBLIC long int __SYSCONF(name)
Xint name; /* property being inspected */
X{
X switch(name) {
X case _SC_ARG_MAX:
X return (long) ARG_MAX;
X
X case _SC_CHILD_MAX:
X return (long) CHILD_MAX;
X
X case _SC_CLK_TCK:
X return (long) CLK_TCK;
X
X case _SC_NGROUPS_MAX:
X return (long) NGROUPS_MAX;
X
X case _SC_OPEN_MAX:
X return (long) OPEN_MAX;
X
X case _SC_JOB_CONTROL:
X return -1L; /* no job control */
X
X case _SC_SAVED_IDS:
X return -1L; /* no saved uid/gid */
X
X case _SC_VERSION:
X return (long) _POSIX_VERSION;
X
X default:
X errno = EINVAL;
X return -1L;
X }
X}
/
echo x - _ttyname.c
sed '/^X/s///' > _ttyname.c << '/'
X/* _ttyname.c POSIX 4.7.2 (underware)
X * char *__TTYNAME(int fildes);
X *
X * Determines name of a terminal device.
X */
X
X#include <lib.h>
X#include <sys/types.h>
X#include <sys/stat.h>
X#include <dirent.h>
X#include <fcntl.h>
X#include <limits.h>
X#include <stddef.h>
X#include <string.h>
X#include <unistd.h>
X
X_PRIVATE char base[] = "/dev";
X_PRIVATE char path[sizeof(base) + 1 + NAME_MAX]; /* extra 1 for '/' */
X
X_PUBLIC char *__TTYNAME(fildes)
Xint fildes;
X{
X DIR *devices;
X struct dirent *entry;
X struct stat tty_stat;
X struct stat dev_stat;
X
X /* Simple first test: file descriptor must be a character device */
X if (__FSTAT(fildes, &tty_stat) < 0 || !S_ISCHR(tty_stat.st_mode))
X return (char *) NULL;
X
X /* Open device directory for reading */
X if ((devices = __OPENDIR(base)) == (DIR *) NULL)
X return (char *) NULL;
X
X /* Scan the entries for one that matches perfectly */
X while ((entry = __READDIR(devices)) != (struct dirent *) NULL) {
X if (tty_stat.st_ino != entry->d_ino)
X continue;
X strcpy(path, base);
X strcat(path, "/");
X strcat(path, entry->d_name);
X if (__STAT(path, &dev_stat) < 0 || !S_ISCHR(dev_stat.st_mode))
X continue;
X if (tty_stat.st_ino == dev_stat.st_ino &&
X tty_stat.st_dev == dev_stat.st_dev &&
X tty_stat.st_rdev == dev_stat.st_rdev) {
X __CLOSEDIR(devices);
X return path;
X }
X }
X
X __CLOSEDIR(devices);
X return (char *) NULL;
X}
/