crond: implement support for setting PATH in crontab files

It's very inconvenient for a cron user not to be able to set a
"personal" PATH for their cron jobs, as is possible with other crons

function                                             old     new   delta
load_crontab                                         868     942     +74
.rodata                                           104878  104884      +6
------------------------------------------------------------------------------
(add/remove: 0/0 grow/shrink: 2/0 up/down: 80/0)               Total: 80 bytes

Signed-off-by: Paul Fox <pgf@foxharp.boston.ma.us>
Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>

1 files changed, 16 insertions, 7 deletions

diff --git a/miscutils/crond.c b/miscutils/crond.c
index 1965af656..bd43c6b68 100644
--- a/miscutils/crond.c
+++ b/miscutils/crond.c
@@ -125,6 +125,7 @@ typedef struct CronLine {
         char *cl_mailto;                /* whom to mail results, may be NULL */
 #endif
         char *cl_shell;
+        char *cl_path;
         /* ordered by size, not in natural order. makes code smaller: */
         char cl_Dow[7];                 /* 0-6, beginning sunday */
         char cl_Mons[12];               /* 0-11 */
@@ -421,6 +422,7 @@ static void load_crontab(const char *fileName)
         char *mailTo = NULL;
 #endif
         char *shell = NULL;
+        char *path = NULL;
 
         delete_cronfile(fileName);
 
@@ -470,7 +472,12 @@ static void load_crontab(const char *fileName)
                                 shell = xstrdup(&tokens[0][6]);
                                 continue;
                         }
-//TODO: handle HOME= too? "man crontab" says:
+                        if (is_prefixed_with(tokens[0], "PATH=")) {
+                                free(path);
+                                path = xstrdup(&tokens[0][5]);
+                                continue;
+                        }
+//TODO: handle HOME= too? Better yet, handle arbitrary ENVVARs? "man crontab" says:
 //name = value
 //
 //where the spaces around the equal-sign (=) are optional, and any subsequent
@@ -480,8 +487,8 @@ static void load_crontab(const char *fileName)
 //
 //Several environment variables are set up automatically by the cron(8) daemon.
 //SHELL is set to /bin/sh, and LOGNAME and HOME are set from the /etc/passwd
-//line of the crontab's owner. HOME and SHELL may be overridden by settings
-//in the crontab; LOGNAME may not.
+//line of the crontab's owner.  HOME, SHELL, and PATH may be overridden by
+//settings in the crontab; LOGNAME may not.
 
 #if ENABLE_FEATURE_CROND_SPECIAL_TIMES
                         if (tokens[0][0] == '@') {
@@ -567,6 +574,7 @@ static void load_crontab(const char *fileName)
                         line->cl_mailto = xstrdup(mailTo);
 #endif
                         line->cl_shell = xstrdup(shell);
+                        line->cl_path = xstrdup(path);
                         /* copy command */
                         line->cl_cmd = xstrdup(tokens[5]);
                         pline = &line->cl_next;
@@ -653,21 +661,22 @@ static void safe_setenv(char **pvar_val, const char *var, const char *val)
 }
 #endif
 
-static void set_env_vars(struct passwd *pas, const char *shell)
+static void set_env_vars(struct passwd *pas, const char *shell, const char *path)
 {
         /* POSIX requires crond to set up at least HOME, LOGNAME, PATH, SHELL.
-         * We assume crond inherited suitable PATH.
          */
 #if SETENV_LEAKS
         safe_setenv(&G.env_var_logname, "LOGNAME", pas->pw_name);
         safe_setenv(&G.env_var_user, "USER", pas->pw_name);
         safe_setenv(&G.env_var_home, "HOME", pas->pw_dir);
         safe_setenv(&G.env_var_shell, "SHELL", shell);
+        if (path) safe_setenv(&G.env_var_shell, "PATH", path);
 #else
         xsetenv("LOGNAME", pas->pw_name);
         xsetenv("USER", pas->pw_name);
         xsetenv("HOME", pas->pw_dir);
         xsetenv("SHELL", shell);
+        if (path) xsetenv("PATH", path);
 #endif
 }
 
@@ -701,7 +710,7 @@ fork_job(const char *user, int mailFd, CronLine *line, bool run_sendmail)
         shell = line->cl_shell ? line->cl_shell : G.default_shell;
         prog = run_sendmail ? SENDMAIL : shell;
 
-        set_env_vars(pas, shell);
+        set_env_vars(pas, shell, NULL); /* don't use crontab's PATH for sendmail */
 
         sv_logmode = logmode;
         pid = vfork();
@@ -845,7 +854,7 @@ static pid_t start_one_job(const char *user, CronLine *line)
 
         /* Prepare things before vfork */
         shell = line->cl_shell ? line->cl_shell : G.default_shell;
-        set_env_vars(pas, shell);
+        set_env_vars(pas, shell, line->cl_path);
 
         /* Fork as the user in question and run program */
         pid = vfork();