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Improve error reporting from validate_exec().

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validate_exec() didn't guarantee to set errno to something appropriate
after a failure, leading to callers not being able to print an on-point
message.  Improve that.

Noted by Kyotaro Horiguchi, though this isn't exactly his proposal.

Discussion: https://postgr.es/m/20220615.131403.1791191615590453058.horikyota.ntt@gmail.com
This commit is contained in:
Tom Lane
2022-07-12 15:37:39 -04:00
parent 7652353d87
commit 920072339f
2 changed files with 16 additions and 11 deletions
Download Patch File Download Diff File Expand all files Collapse all files

11
src/bin/pg_upgrade/exec.c
View File

@ -423,18 +423,11 @@ check_exec(const char *dir, const char *program, bool check_version)
char line[MAXPGPATH]; char line[MAXPGPATH];
char cmd[MAXPGPATH]; char cmd[MAXPGPATH];
char versionstr[128]; char versionstr[128];
int ret;
snprintf(path, sizeof(path), "%s/%s", dir, program); snprintf(path, sizeof(path), "%s/%s", dir, program);
ret = validate_exec(path); if (validate_exec(path) != 0)
pg_fatal("check for \"%s\" failed: %m", path);
if (ret == -1)
pg_fatal("check for \"%s\" failed: does not exist or cannot be executed",
path);
else if (ret == -2)
pg_fatal("check for \"%s\" failed: cannot read (permission denied)",
path);
snprintf(cmd, sizeof(cmd), "\"%s\" -V", path); snprintf(cmd, sizeof(cmd), "\"%s\" -V", path);

16
src/common/exec.c
View File

@ -74,6 +74,7 @@ static BOOL GetTokenUser(HANDLE hToken, PTOKEN_USER *ppTokenUser);
* returns 0 if the file is found and no error is encountered. * returns 0 if the file is found and no error is encountered.
* -1 if the regular file "path" does not exist or cannot be executed. * -1 if the regular file "path" does not exist or cannot be executed.
* -2 if the file is otherwise valid but cannot be read. * -2 if the file is otherwise valid but cannot be read.
* in the failure cases, errno is set appropriately
*/ */
int int
validate_exec(const char *path) validate_exec(const char *path)
@ -105,7 +106,16 @@ validate_exec(const char *path)
return -1; return -1;
if (!S_ISREG(buf.st_mode)) if (!S_ISREG(buf.st_mode))
{
/*
* POSIX offers no errno code that's simply "not a regular file". If
* it's a directory we can use EISDIR. Otherwise, it's most likely a
* device special file, and EPERM (Operation not permitted) isn't too
* horribly off base.
*/
errno = S_ISDIR(buf.st_mode) ? EISDIR : EPERM;
return -1; return -1;
}
/* /*
* Ensure that the file is both executable and readable (required for * Ensure that the file is both executable and readable (required for
@ -114,9 +124,11 @@ validate_exec(const char *path)
#ifndef WIN32 #ifndef WIN32
is_r = (access(path, R_OK) == 0); is_r = (access(path, R_OK) == 0);
is_x = (access(path, X_OK) == 0); is_x = (access(path, X_OK) == 0);
/* access() will set errno if it returns -1 */
#else #else
is_r = buf.st_mode & S_IRUSR; is_r = buf.st_mode & S_IRUSR;
is_x = buf.st_mode & S_IXUSR; is_x = buf.st_mode & S_IXUSR;
errno = EACCES; /* appropriate thing if we return nonzero */
#endif #endif
return is_x ? (is_r ? 0 : -2) : -1; return is_x ? (is_r ? 0 : -2) : -1;
} }
@ -165,7 +177,7 @@ find_my_exec(const char *argv0, char *retpath)
return resolve_symlinks(retpath); return resolve_symlinks(retpath);
log_error(errcode(ERRCODE_WRONG_OBJECT_TYPE), log_error(errcode(ERRCODE_WRONG_OBJECT_TYPE),
_("invalid binary \"%s\""), retpath); _("invalid binary \"%s\": %m"), retpath);
return -1; return -1;
} }
@ -215,7 +227,7 @@ find_my_exec(const char *argv0, char *retpath)
break; break;
case -2: /* found but disqualified */ case -2: /* found but disqualified */
log_error(errcode(ERRCODE_WRONG_OBJECT_TYPE), log_error(errcode(ERRCODE_WRONG_OBJECT_TYPE),
_("could not read binary \"%s\""), _("could not read binary \"%s\": %m"),
retpath); retpath);
break; break;
} }