Use setenv() in preference to putenv().

Since at least 2001 we've used putenv() and avoided setenv(), on the
grounds that the latter was unportable and not in POSIX.  However,
POSIX added it that same year, and by now the situation has reversed:
setenv() is probably more portable than putenv(), since POSIX now
treats the latter as not being a core function.  And setenv() has
cleaner semantics too.  So, let's reverse that old policy.

This commit adds a simple src/port/ implementation of setenv() for
any stragglers (we have one in the buildfarm, but I'd not be surprised
if that code is never used in the field).  More importantly, extend
win32env.c to also support setenv().  Then, replace usages of putenv()
with setenv(), and get rid of some ad-hoc implementations of setenv()
wannabees.

Also, adjust our src/port/ implementation of unsetenv() to follow the
POSIX spec that it returns an error indicator, rather than returning
void as per the ancient BSD convention.  I don't feel a need to make
all the call sites check for errors, but the portability stub ought
to match real-world practice.

Discussion: https://postgr.es/m/2065122.1609212051@sss.pgh.pa.us

1 files changed, 1 insertions, 10 deletions

diff --git a/src/bin/psql/command.c b/src/bin/psql/command.c
index 38b588882d1..c545341cddd 100644
--- a/src/bin/psql/command.c
+++ b/src/bin/psql/command.c
@@ -2296,17 +2296,8 @@ exec_command_setenv(PsqlScanState scan_state, bool active_branch,
 		else
 		{
 			/* Set variable to the value of the next argument */
-			char	   *newval;
-
-			newval = psprintf("%s=%s", envvar, envval);
-			putenv(newval);
+			setenv(envvar, envval, 1);
 			success = true;
-
-			/*
-			 * Do not free newval here, it will screw up the environment if
-			 * you do. See putenv man page for details. That means we leak a
-			 * bit of memory here, but not enough to worry about.
-			 */
 		}
 		free(envvar);
 		free(envval);