prctl: init at 1.7

{

  lib,

  stdenv,

  fetchFromGitHub,

  autoreconfHook,

  versionCheckHook,

  nix-update-script,

  bash,

}:

stdenv.mkDerivation (finalAttrs: {

  pname = "prctl";

  version = "1.7";

  src = fetchFromGitHub {

    owner = "hikerockies";

    repo = "prctl";

    tag = "v${finalAttrs.version}";

    hash = "sha256-1b8SO70mp0ACL3hw/iwKpPUpI5G7hF7l84hlSDHB2oA=";

  };

  strictDeps = true;

  nativeBuildInputs = [ autoreconfHook ];

  nativeInstallCheckInputs = [ versionCheckHook ];

  patches = [

    # Eliminate unsafe strcpy() calls,

    # cf. <https://github.com/hikerockies/prctl/pull/1>

    ./prctl-strcpy-overflow.patch

    # Correct option parsing,

    # cf. <https://github.com/hikerockies/prctl/pull/2>

    ./prctl-getopt.patch

  ];

  postPatch = ''

    substituteInPlace prctl.c \

      --replace-fail '"/bin/bash"' '"${lib.getExe bash}"'

  '';

  doInstallCheck = true;

  passthru.updateScript = nix-update-script { };

  meta = {

    description = "Tool to query and modify process behaviour";

    homepage = "https://tracker.debian.org/pkg/prctl";

    changelog = "https://github.com/hikerockies/prctl/blob/v${finalAttrs.version}/ChangeLog";

    mainProgram = "prctl";

    maintainers = with lib.maintainers; [ mvs ];

    license = lib.licenses.gpl2Only;

    platforms = lib.platforms.linux;

  };

})

From 6745b6362681f57823a57575a7949bd510767ac4 Mon Sep 17 00:00:00 2001

From: Mikael Voss <mvs@nyantec.com>

Date: Wed, 23 Jul 2025 18:37:10 +0200

Subject: [PATCH 1/2] Replace unsound use of EOF

MIME-Version: 1.0

Content-Type: text/plain; charset=UTF-8

Content-Transfer-Encoding: 8bit

While getopt_long returns -1 on error, EOF is an implementation‐defined

negative integer constant that just happens to be defined as -1 by most

C standard libraries.

---

 prctl.c | 4 ++--

 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/prctl.c b/prctl.c

index 38cbcd1..527584c 100644

--- a/prctl.c

+++ b/prctl.c

@@ -299,8 +299,8 @@ main(int argc, char **argv)

 		exit(1);

 	}

 	opterr = 0;

-	while ((opt = getopt_long(argc, argv, "+qhv", longopts, 

-					(int *) NULL)) != EOF) {

+	while ((opt = getopt_long(argc, argv, "+qhv", longopts,

+					(int *) NULL)) != -1) {

 		switch (opt) {

 		case 'u':

 			if (strcmp(optarg, "silent") == 0) {

From 0c11b937c30e41e97c3fa852f6d65cd595bc193f Mon Sep 17 00:00:00 2001

From: Mikael Voss <mvs@nyantec.com>

Date: Wed, 23 Jul 2025 18:54:39 +0200

Subject: [PATCH 2/2] Properly display invalid long options

---

 prctl.c | 4 ++--

 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/prctl.c b/prctl.c

index 527584c..4c1d632 100644

--- a/prctl.c

+++ b/prctl.c

@@ -375,8 +375,8 @@ main(int argc, char **argv)

 			break;

 		case '?':

-			fprintf(stderr, "%s: invalid option - %c\n", 

-					progname, optopt);

+			fprintf(stderr, "%s: invalid option: %s\n",

+					progname, argv[optind - 1]);

 			exit(1);

 			break;

 		}

From 079877486d9bbe170de2fbc3cba37713d11ab224 Mon Sep 17 00:00:00 2001

From: Mikael Voss <mvs@nyantec.com>

Date: Wed, 23 Jul 2025 17:33:04 +0200

Subject: [PATCH 1/2] Avoid unnecessary copy of argv[0]

MIME-Version: 1.0

Content-Type: text/plain; charset=UTF-8

Content-Transfer-Encoding: 8bit

The programme is copying the contents of *argv[0] into a fixed‐size

buffer of 512 bytes using strcpy(). This might result in a buffer

overflow and is unnecessary as the contents are never modified.

---

 prctl.c | 12 +++++-------

 1 file changed, 5 insertions(+), 7 deletions(-)

diff --git a/prctl.c b/prctl.c

index 38cbcd1..b8cb85b 100644

--- a/prctl.c

+++ b/prctl.c

@@ -51,13 +51,13 @@ struct option longopts[] = {

 int verbose=0;

 void

-print_version(char *progname)

+print_version(char const *progname)

 {

 	printf("%s version %s\n", progname, VERSION);

 }

 void

-usage(char *progname)

+usage(char const *progname)

 {

 	print_version(progname);

 	printf("Usage: %s [-v] [-h|--help] [--version]\n", progname);

@@ -273,8 +273,7 @@ int

 main(int argc, char **argv)

 {

 	int opt, cmd_start;

-	char *progname;

-	char fullpath[512];

+	char const *progname;

 	char shellname[128];

 	int unaligned_val = -99;

 	int fpemu_val = -99;

@@ -284,11 +283,10 @@ main(int argc, char **argv)

 	int display_all = 0;

 	int umask;

-	strcpy(fullpath, argv[0]);

-	if ((progname = strrchr(fullpath, '/')) != NULL) {

+	if ((progname = strrchr(argv[0], '/')) != NULL) {

 		progname++;

 	} else {

-		progname = fullpath;

+		progname = argv[0];

 	}

 	/*

From c233d083cec389e10dc9e85b3a835cf81246c275 Mon Sep 17 00:00:00 2001

From: Mikael Voss <mvs@nyantec.com>

Date: Wed, 23 Jul 2025 17:57:59 +0200

Subject: [PATCH 2/2] Avoid unnecessary copy of shell path

MIME-Version: 1.0

Content-Type: text/plain; charset=UTF-8

Content-Transfer-Encoding: 8bit

The programme tries getenv("SHELL") and getpwuid(getuid())->pw_shell to

determine the preferred shell, falling back to DEFAULT_SHELL, and

copies the contents pointed to into a fixed‐sized buffer of 128 bytes

using strcpy().

This could result in a buffer overflow and is not necessary: While both

getenv() and getpwuid() return pointers to locations which might get

modified by subsequent calls to their respective function families,

they are only called once, so that these pointers can be aliased safely.

In addition, getenv("SHELL") would return a null pointer if the variable

is unset in the environment, resulting in a null pointer dereference in

the enclosing strcpy() call.

---

 prctl.c | 22 +++++++++-------------

 1 file changed, 9 insertions(+), 13 deletions(-)

diff --git a/prctl.c b/prctl.c

index b8cb85b..342419c 100644

--- a/prctl.c

+++ b/prctl.c

@@ -274,7 +274,7 @@ main(int argc, char **argv)

 {

 	int opt, cmd_start;

 	char const *progname;

-	char shellname[128];

+	char const *shellname;

 	int unaligned_val = -99;

 	int fpemu_val = -99;

 	int mcekill_val = -99;

@@ -443,31 +443,27 @@ main(int argc, char **argv)

 		}

 		printf("Starting a shell\n");

-		strcpy(shellname, getenv("SHELL"));

-		

+		shellname = getenv("SHELL");

+

 		/*

 		 * Make sure SHELL environment variable is not unset. If it

-		 * is, start bash.

+		 * is, start user login shell or bash.

 		 */

-		if (shellname[0] == 0) {

+		if (shellname == NULL) {

 			struct passwd *pwd_entry;

 			pwd_entry = getpwuid(getuid());

-			if (pwd_entry == NULL) {

-				strcpy(shellname, DEFAULT_SHELL);

+			if (pwd_entry != NULL && pwd_entry->pw_shell != NULL) {

+				shellname = pwd_entry->pw_shell;

 			} else {

-				if (pwd_entry->pw_shell != NULL) {

-					strcpy(shellname, pwd_entry->pw_shell);

-				} else {

-					strcpy(shellname, DEFAULT_SHELL);

-				}

+				shellname = DEFAULT_SHELL;

 			}

 		}

 		/*

 		 * Now exec the shell

 		 */

-		if (execlp(shellname, (char *)shellname, (char *) 0) == -1) {

+		if (execlp(shellname, shellname, (char *) 0) == -1) {

 			fprintf(stderr, "Failed to exec the shell: %s\n",

 				strerror(errno));

 			exit(1);