commit 2facbf83dae38e4892140153bd47fb837b0d2c48
Author: Mikolaj Golub <trociny@freebsd.org>
Date:   Sat Dec 15 22:26:05 2012 +0200

    Extend libprocstat with functions to retrieve process command line
    arguments and environment variables.

diff --git a/lib/libprocstat/Symbol.map b/lib/libprocstat/Symbol.map
index 0509066..c445f55 100644
--- a/lib/libprocstat/Symbol.map
+++ b/lib/libprocstat/Symbol.map
@@ -3,12 +3,16 @@
  */
 FBSD_1.2 {
 	procstat_close;
+	procstat_freeargv;
+	procstat_freeenvv;
 	procstat_freefiles;
 	procstat_freeprocs;
 	procstat_get_pipe_info;
 	procstat_get_pts_info;
 	procstat_get_socket_info;
 	procstat_get_vnode_info;
+	procstat_getargv;
+	procstat_getenvv;
 	procstat_getfiles;
 	procstat_getprocs;
 	procstat_open_kvm;
diff --git a/lib/libprocstat/libprocstat.3 b/lib/libprocstat/libprocstat.3
index dd163c2..7be2dbe 100644
--- a/lib/libprocstat/libprocstat.3
+++ b/lib/libprocstat/libprocstat.3
@@ -24,15 +24,19 @@
 .\"
 .\" $FreeBSD$
 .\"
-.Dd April 1, 2012
+.Dd December 15, 2012
 .Dt LIBPROCSTAT 3
 .Os
 .Sh NAME
 .Nm procstat_open_kvm ,
 .Nm procstat_open_sysctl ,
 .Nm procstat_close ,
+.Nm procstat_getargv ,
+.Nm procstat_getenvv ,
 .Nm procstat_getfiles ,
 .Nm procstat_getprocs ,
+.Nm procstat_freeargv ,
+.Nm procstat_freeenvv ,
 .Nm procstat_freefiles ,
 .Nm procstat_freeprocs ,
 .Nm procstat_get_pipe_info ,
@@ -50,6 +54,14 @@
 .Ft void
 .Fn procstat_close "struct procstat *procstat"
 .Ft void
+.Fo procstat_freeargv
+.Fa "struct procstat *procstat"
+.Fc
+.Ft void
+.Fo procstat_freeenvv
+.Fa "struct procstat *procstat"
+.Fc
+.Ft void
 .Fo procstat_freefiles
 .Fa "struct procstat *procstat"
 .Fa "struct filestat_list *head"
@@ -91,6 +103,20 @@
 .Fa "struct vnstat *vn"
 .Fa "char *errbuf"
 .Fc
+.Ft "char **"
+.Fo procstat_getargv
+.Fa "struct procstat *procstat"
+.Fa "const struct kinfo_proc *kp"
+.Fa "size_t nchr"
+.Fa "char *errbuf"
+.Fc
+.Ft "char **"
+.Fo procstat_getenvv
+.Fa "struct procstat *procstat"
+.Fa "const struct kinfo_proc *kp"
+.Fa "size_t nchr"
+.Fa "char *errbuf"
+.Fc
 .Ft "struct filestat_list *"
 .Fo procstat_getfiles
 .Fa "struct procstat *procstat"
@@ -179,6 +205,50 @@ The caller is responsible to free the allocated memory with a subsequent
 function call.
 .Pp
 The
+.Fn procstat_getargv
+function gets a pointer to the
+.Vt procstat
+structure from one of the
+.Fn procstat_open_*
+functions, a pointer to
+.Vt kinfo_proc
+structure from the array obtained from the
+.Fn kvm_getprocs
+function, and returns a null-terminated argument vector that corresponds to
+the command line arguments passed to the process.
+The
+.Fa nchr
+argument indicates the maximum number of characters, including null bytes,
+to use in building the strings.
+If this amount is exceeded, the string causing the overflow is truncated and
+the partial result is returned.
+This is handy for programs that print only a one line summary of a
+command and should not copy out large amounts of text only to ignore it.
+If
+.Fa nchr
+is zero, no limit is imposed and all argument strings are returned.
+The values of the returned argument vector refer the strings stored
+in the
+.Vt procstat
+internal buffer.
+A subsequent call of the function with the same
+.Vt procstat
+argument will reuse the buffer.
+To free the allocated memory
+.Fn procstat_freeargv
+function call can be used, or it will be released on
+.Fn procstat_close .
+.Pp
+The
+.Fn procstat_getenvv
+function is similar to
+.Fn procstat_getargv
+but returns the vector of environment strings.
+The caller may free the allocated memory with a subsequent
+.Fn procstat_freeenv
+function call.
+.Pp
+The
 .Fn procstat_getfiles
 function gets a pointer to the
 .Vt procstat
diff --git a/lib/libprocstat/libprocstat.c b/lib/libprocstat/libprocstat.c
index 9d9c111..ad59c09 100644
--- a/lib/libprocstat/libprocstat.c
+++ b/lib/libprocstat/libprocstat.c
@@ -137,6 +137,8 @@ procstat_close(struct procstat *procstat)
 	assert(procstat);
 	if (procstat->type == PROCSTAT_KVM)
 		kvm_close(procstat->kd);
+	procstat_freeargv(procstat);
+	procstat_freeenvv(procstat);
 	free(procstat);
 }
 
@@ -1402,3 +1404,177 @@ getmnton(kvm_t *kd, struct mount *m)
 	mhead = mt;
 	return (mt->mntonname);
 }
+
+/*
+ * Auxiliary structures and functions to get process environment or
+ * command line arguments.
+ */
+struct argvec {
+	char	*buf;
+	size_t	bufsize;
+	char	**argv;
+	size_t	argc;
+};
+
+static struct argvec *
+argvec_alloc(size_t bufsize)
+{
+	struct argvec *av;
+
+	av = malloc(sizeof(*av));
+	if (av == NULL)
+		return (NULL);
+	av->bufsize = bufsize;
+	av->buf = malloc(av->bufsize);
+	if (av->buf == NULL) {
+		free(av);
+		return (NULL);
+	}
+	av->argc = 32;
+	av->argv = malloc(av->argc);
+	if (av->argv == NULL) {
+		free(av->buf);
+		free(av);
+		return (NULL);
+	}
+	return av;
+}
+
+static void
+argvec_free(struct argvec * av)
+{
+
+	free(av->argv);
+	free(av->buf);
+	free(av);
+}
+
+static char **
+getargv(struct procstat *procstat, const struct kinfo_proc *kp, size_t nchr,
+    int env, char *errbuf)
+{
+	int error, name[4], argc, i;
+	size_t len;
+	char *p, **argv;
+	struct argvec *av, **avp;
+
+	assert(procstat);
+	assert(kp);
+	if (procstat->type == PROCSTAT_KVM) {
+		warnx("can't use kvm access method");
+		snprintf(errbuf, _POSIX2_LINE_MAX, "error");
+		return (NULL);
+	}
+	if (procstat->type != PROCSTAT_SYSCTL) {
+		warnx("unknown access method: %d", procstat->type);
+		snprintf(errbuf, _POSIX2_LINE_MAX, "error");
+		return (NULL);
+	}
+
+	if (nchr == 0 || nchr > ARG_MAX)
+		nchr = ARG_MAX;
+
+	avp = (struct argvec **)(env ? &procstat->argv : &procstat->envv);
+	av = *avp;
+
+	if (av == NULL)
+	{
+		av = argvec_alloc(nchr);
+		if (av == NULL)
+		{
+			warnx("malloc(%zu)", nchr);
+			snprintf(errbuf, _POSIX2_LINE_MAX, "error");
+			return (NULL);
+		}
+		*avp = av;
+	} else if (av->bufsize < nchr) {
+		av->buf = reallocf(av->buf, nchr);
+		if (av->buf == NULL) {
+			warnx("malloc(%zu)", nchr);
+			snprintf(errbuf, _POSIX2_LINE_MAX, "error");
+			return (NULL);
+		}
+	}
+
+	name[0] = CTL_KERN;
+	name[1] = KERN_PROC;
+	name[2] = env ? KERN_PROC_ENV : KERN_PROC_ARGS;
+	name[3] = kp->ki_pid;
+	len = nchr;
+	error = sysctl(name, 4, av->buf, &len, NULL, 0);
+	if (error != 0 && errno != ESRCH && errno != EPERM) {
+		warn("sysctl(kern.proc.%s)", env ? "env" : "args");
+		snprintf(errbuf, _POSIX2_LINE_MAX, "error");
+	}
+	if (error != 0 || len == 0)
+		return (NULL);
+
+	argv = av->argv;
+	argc = av->argc;
+	i = 0;
+	for (p = av->buf; p < av->buf + len; p += strlen(p) + 1) {
+		argv[i++] = p;
+		if (i < argc)
+			continue;
+		/* Grow argv. */
+		argc += argc;
+		argv = reallocf(argv, sizeof(char *) * argc);
+		if (argv == NULL) {
+			warnx("malloc(%zu)", sizeof(char *) * argc);
+			snprintf(errbuf, _POSIX2_LINE_MAX, "error");
+			return (NULL);
+		}
+		av->argv = argv;
+		av->argc = argc;
+	}
+	argv[i] = NULL;
+
+	return (argv);
+}
+
+/*
+ * Return process command line arguments.
+ */
+char **
+procstat_getargv(struct procstat *procstat, const struct kinfo_proc *p,
+    size_t nchr, char *errbuf)
+{
+
+	return (getargv(procstat, p, nchr, 0, errbuf));
+}
+
+/*
+ * Free the buffer allocated by procstat_getargv().
+ */
+void
+procstat_freeargv(struct procstat *procstat)
+{
+
+	if (procstat->argv != NULL) {
+		argvec_free(procstat->argv);
+		procstat->argv = NULL;
+	}
+}
+
+/*
+ * Return process environment.
+ */
+char **
+procstat_getenvv(struct procstat *procstat, const struct kinfo_proc *p,
+    size_t nchr, char *errbuf)
+{
+
+	return (getargv(procstat, p, nchr, 1, errbuf));
+}
+
+/*
+ * Free the buffer allocated by procstat_getenvv().
+ */
+void
+procstat_freeenvv(struct procstat *procstat)
+{
+	if (procstat->envv != NULL) {
+		argvec_free(procstat->envv);
+		procstat->envv = NULL;
+	}
+}
diff --git a/lib/libprocstat/libprocstat.h b/lib/libprocstat/libprocstat.h
index 662ea37..f6ed981 100644
--- a/lib/libprocstat/libprocstat.h
+++ b/lib/libprocstat/libprocstat.h
@@ -146,9 +146,15 @@ STAILQ_HEAD(filestat_list, filestat);
 
 __BEGIN_DECLS
 void	procstat_close(struct procstat *procstat);
+void	procstat_freeargv(struct procstat *procstat);
+void	procstat_freeenvv(struct procstat *procstat);
 void	procstat_freeprocs(struct procstat *procstat, struct kinfo_proc *p);
 void	procstat_freefiles(struct procstat *procstat,
     struct filestat_list *head);
+char	**procstat_getargv(struct procstat *procstat,
+    const struct kinfo_proc *p, size_t nchr, char *errbuf);
+char	**procstat_getenvv(struct procstat *procstat,
+    const struct kinfo_proc *p, size_t nchr, char *errbuf);
 struct filestat_list	*procstat_getfiles(struct procstat *procstat,
     struct kinfo_proc *kp, int mmapped);
 struct kinfo_proc	*procstat_getprocs(struct procstat *procstat,
diff --git a/lib/libprocstat/libprocstat_internal.h b/lib/libprocstat/libprocstat_internal.h
index 1c1d842..8ba1cf7 100644
--- a/lib/libprocstat/libprocstat_internal.h
+++ b/lib/libprocstat/libprocstat_internal.h
@@ -34,6 +34,8 @@ struct procstat {
 	kvm_t	*kd;
 	void	*vmentries;
 	void	*files;
+	void	*argv;
+	void	*envv;
 };
 
 #endif	/* !_LIBPROCSTAT_INTERNAL_H_ */

commit 4a69b2757baeb6fce81205ff5daa9510076877ff
Author: Mikolaj Golub <trociny@freebsd.org>
Date:   Sat Dec 15 22:29:06 2012 +0200

    Use libprocstat(3) to retrieve process command line arguments and
    environment variables.

diff --git a/usr.bin/procstat/procstat.c b/usr.bin/procstat/procstat.c
index b0cee6b..3d453cf 100644
--- a/usr.bin/procstat/procstat.c
+++ b/usr.bin/procstat/procstat.c
@@ -61,9 +61,9 @@ procstat(struct procstat *prstat, struct kinfo_proc *kipp)
 	if (bflag)
 		procstat_bin(kipp);
 	else if (cflag)
-		procstat_args(kipp);
+		procstat_args(prstat, kipp);
 	else if (eflag)
-		procstat_env(kipp);
+		procstat_env(prstat, kipp);
 	else if (fflag)
 		procstat_files(prstat, kipp);
 	else if (iflag)
diff --git a/usr.bin/procstat/procstat.h b/usr.bin/procstat/procstat.h
index e65436d..065230e 100644
--- a/usr.bin/procstat/procstat.h
+++ b/usr.bin/procstat/procstat.h
@@ -34,12 +34,12 @@ extern int	hflag, nflag, Cflag;
 struct kinfo_proc;
 void	kinfo_proc_sort(struct kinfo_proc *kipp, int count);
 
-void	procstat_args(struct kinfo_proc *kipp);
+void	procstat_args(struct procstat *prstat, struct kinfo_proc *kipp);
 void	procstat_auxv(struct kinfo_proc *kipp);
 void	procstat_basic(struct kinfo_proc *kipp);
 void	procstat_bin(struct kinfo_proc *kipp);
 void	procstat_cred(struct kinfo_proc *kipp);
-void	procstat_env(struct kinfo_proc *kipp);
+void	procstat_env(struct procstat *prstat, struct kinfo_proc *kipp);
 void	procstat_files(struct procstat *prstat, struct kinfo_proc *kipp);
 void	procstat_kstack(struct kinfo_proc *kipp, int kflag);
 void	procstat_rlimit(struct kinfo_proc *kipp);
diff --git a/usr.bin/procstat/procstat_args.c b/usr.bin/procstat/procstat_args.c
index b13aa72..3c21642 100644
--- a/usr.bin/procstat/procstat_args.c
+++ b/usr.bin/procstat/procstat_args.c
@@ -40,52 +40,42 @@
 
 #include "procstat.h"
 
-static char args[ARG_MAX];
+static char errbuf[_POSIX2_LINE_MAX];
 
 static void
-do_args(struct kinfo_proc *kipp, int env)
+do_args(struct procstat *procstat, struct kinfo_proc *kipp, int env)
 {
-	int error, name[4];
-	size_t len;
-	char *cp;
+	int i;
+	char **args;
 
-	if (!hflag)
+	if (!hflag) {
 		printf("%5s %-16s %-53s\n", "PID", "COMM",
 		    env ? "ENVIRONMENT" : "ARGS");
-
-	name[0] = CTL_KERN;
-	name[1] = KERN_PROC;
-	name[2] = env ? KERN_PROC_ENV : KERN_PROC_ARGS;
-	name[3] = kipp->ki_pid;
-	len = sizeof(args);
-	error = sysctl(name, 4, args, &len, NULL, 0);
-	if (error < 0 && errno != ESRCH && errno != EPERM) {
-		warn("sysctl: kern.proc.%s: %d: %d", env ? "env" : "args",
-		    kipp->ki_pid, errno);
-		return;
 	}
-	if (error < 0)
+
+	args = env ? procstat_getenvv(procstat, kipp, 0, errbuf) :
+	    procstat_getargv(procstat, kipp, 0, errbuf);
+
+	printf("%5d %-16s", kipp->ki_pid, kipp->ki_comm);
+
+	if (args == NULL) {
+		printf(" -\n");
 		return;
-	if (len == 0 || strlen(args) == 0) {
-		strcpy(args, "-");
-		len = strlen(args) + 1;
 	}
 
-	printf("%5d ", kipp->ki_pid);
-	printf("%-16s ", kipp->ki_comm);
-	for (cp = args; cp < args + len; cp += strlen(cp) + 1)
-		printf("%s%s", cp != args ? " " : "", cp);
+	for (i = 0; args[i] != NULL; i++)
+		printf(" %s", args[i]);
 	printf("\n");
 }
 
 void
-procstat_args(struct kinfo_proc *kipp)
+procstat_args(struct procstat *procstat, struct kinfo_proc *kipp)
 {
-	do_args(kipp, 0);
+	do_args(procstat, kipp, 0);
 }
 
 void
-procstat_env(struct kinfo_proc *kipp)
+procstat_env(struct procstat *procstat, struct kinfo_proc *kipp)
 {
-	do_args(kipp, 1);
+	do_args(procstat, kipp, 1);
 }