From 0236fbc21c7f6bcd0bb262c6d6d0519f86c2e28e Mon Sep 17 00:00:00 2001
From: Volker Wysk <post@volker-wysk.de>
Date: Fri, 29 Mar 2019 14:34:27 +1100
Subject: [PATCH] extras/posix: Extend exec module.

extras/posix/posix.exec.m:
    Add execvp, execv, execve predicates.
---
 extras/posix/posix.exec.m | 93 ++++++++++++++++++++++++++++++++++-----
 1 file changed, 82 insertions(+), 11 deletions(-)

diff --git a/extras/posix/posix.exec.m b/extras/posix/posix.exec.m
index bb336dc00..e94de0625 100644
--- a/extras/posix/posix.exec.m
+++ b/extras/posix/posix.exec.m
@@ -24,9 +24,22 @@
 
 :- type env == map(string, string).
 
+:- pred execvp(string::in, argv::in, posix.result::out,
+    io::di, io::uo) is det.
+
+:- pred execv(string::in, argv::in, posix.result::out,
+    io::di, io::uo) is det.
+
+:- pred execve(string::in, argv::in, env::in, posix.result::out,
+    io::di, io::uo) is det.
+
 :- pred exec(string::in, argv::in, env::in, posix.result::out,
     io::di, io::uo) is det.
 
+% This is a GNU extension, and not included:
+% :- pred execvpe(string::in, argv::in, env::in, posix.result::out,
+%   io::di, io::uo) is det.
+
 %-----------------------------------------------------------------------------%
 %-----------------------------------------------------------------------------%
 
@@ -72,23 +85,26 @@
     Array[i] = NULL;
 ").
 
-%-----------------------------------------------------------------------------%
-
-exec(Command, Args, Env, Result, !IO) :-
-    make_string_array(Args, ArgsArray),
-    make_string_array(map(variable, map.to_assoc_list(Env)), EnvArray),
-    exec0(Command, ArgsArray, EnvArray, !IO),
-    errno(Err, !IO),
-    Result = error(Err).
-
 :- func variable(pair(string)) = string.
 
 variable(Name - Value) = Name ++ "=" ++ Value.
 
-:- pred exec0(string::in, string_array::in, string_array::in, io::di, io::uo)
+%-----------------------------------------------------------------------------%
+%
+% int execve(const char *filename, char *const argv[], char *const envp[]);
+%
+
+execve(Command, Args, Env, Result, !IO) :-
+    make_string_array(Args, ArgsArray),
+    make_string_array(map(variable, map.to_assoc_list(Env)), EnvArray),
+    execve0(Command, ArgsArray, EnvArray, !IO),
+    errno(Err, !IO),
+    Result = error(Err).
+
+:- pred execve0(string::in, string_array::in, string_array::in, io::di, io::uo)
     is det.
 :- pragma foreign_proc("C",
-    exec0(Command::in, ArgsArray::in, EnvArray::in, _IO0::di, _IO::uo),
+    execve0(Command::in, ArgsArray::in, EnvArray::in, _IO0::di, _IO::uo),
     [promise_pure, will_not_call_mercury, tabled_for_io],
 "
     int ret;
@@ -98,6 +114,61 @@ variable(Name - Value) = Name ++ "=" ++ Value.
     } while (ret == -1 && MR_is_eintr(errno));
 ").
 
+%-----------------------------------------------------------------------------%
+%
+% int execvp(const char *file, char *const argv[]);
+%
+
+execvp(Command, Args, Result, !IO) :-
+    make_string_array(Args, ArgsArray),
+    execvp0(Command, ArgsArray, !IO),
+    errno(Err, !IO),
+    Result = error(Err).
+
+:- pred execvp0(string::in, string_array::in, io::di, io::uo)
+    is det.
+:- pragma foreign_proc("C",
+    execvp0(Command::in, ArgsArray::in, _IO0::di, _IO::uo),
+    [promise_pure, will_not_call_mercury, tabled_for_io],
+"
+    int ret;
+
+    do {
+        ret = execvp(Command, ArgsArray);
+    } while (ret == -1 && MR_is_eintr(errno));
+").
+
+%-----------------------------------------------------------------------------%
+%
+% int execv(const char *path, char *const argv[]);
+%
+
+execv(Command, Args, Result, !IO) :-
+    make_string_array(Args, ArgsArray),
+    execv0(Command, ArgsArray, !IO),
+    errno(Err, !IO),
+    Result = error(Err).
+
+:- pred execv0(string::in, string_array::in, io::di, io::uo)
+    is det.
+:- pragma foreign_proc("C",
+    execv0(Command::in, ArgsArray::in, _IO0::di, _IO::uo),
+    [promise_pure, will_not_call_mercury, tabled_for_io],
+"
+    int ret;
+
+    do {
+        ret = execv(Command, ArgsArray);
+    } while (ret == -1 && MR_is_eintr(errno));
+").
+
+%-----------------------------------------------------------------------------%
+%
+% Synonym for execve, for backwards compatibility
+
+exec(Command, Args, Env, Result, !IO) :-
+    execve(Command, Args, Env, Result, !IO).
+
 %-----------------------------------------------------------------------------%
 :- end_module posix.exec.
 %-----------------------------------------------------------------------------%