[Bug 3544683]: Backport of reentrancy fix for super-POSIX correctness of the

passwd/group access functions.

2 files changed, 225 insertions, 54 deletions

diff --git a/ChangeLog b/ChangeLog
index aecbf9c..ae28d4f 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,12 @@
+2012-07-16  Donal K. Fellows  <dkf@users.sf.net>
+
+	* unix/tclUnixCompat.c (TclpGetPwNam, TclpGetPwUid, TclpGetGrNam)
+	(TclpGetGrGid): [Bug 3544683]: Use the elaborate memory management
+	scheme outlined on http://www.opengroup.org/austin/docs/austin_328.txt
+	to handle Tcl's use of standard reentrant versions of the passwd/group
+	access functions so that everything can work on all BSDs. Problem
+	identified by Stuart Cassoff.
+
 2012-07-11  Jan Nijtmans  <nijtmans@users.sf.net>
 
 	* win/tclWinReg.c: [Bug #3362446]: registry keys command fails
diff --git a/unix/tclUnixCompat.c b/unix/tclUnixCompat.c
index f582c0c..8b067af 100644
--- a/unix/tclUnixCompat.c
+++ b/unix/tclUnixCompat.c
@@ -13,8 +13,10 @@
 #include <errno.h>
 #include <string.h>
 
-/* See also: SC_BLOCKING_STYLE in unix/tcl.m4
+/*
+ * See also: SC_BLOCKING_STYLE in unix/tcl.m4
  */
+
 #ifdef	USE_FIONBIO
 #   ifdef HAVE_SYS_FILIO_H
 #	include	<sys/filio.h>	/* For FIONBIO. */
@@ -23,39 +25,6 @@
 #	include	<sys/ioctl.h>
 #   endif
 #endif	/* USE_FIONBIO */
-
-/*
- *---------------------------------------------------------------------------
- *
- * TclUnixSetBlockingMode --
- *
- *	Set the blocking mode of a file descriptor.
- *
- * Results:
- *
- *	0 on success, -1 (with errno set) on error.
- *
- *---------------------------------------------------------------------------
- */
-int
-TclUnixSetBlockingMode(
-    int fd,		/* File descriptor */
-    int mode)		/* TCL_MODE_BLOCKING or TCL_MODE_NONBLOCKING */
-{
-#ifndef USE_FIONBIO
-    int flags = fcntl(fd, F_GETFL);
-
-    if (mode == TCL_MODE_BLOCKING) {
-	flags &= ~O_NONBLOCK;
-    } else {
-	flags |= O_NONBLOCK;
-    }
-    return fcntl(fd, F_SETFL, flags);
-#else /* USE_FIONBIO */
-    int state = (mode == TCL_MODE_NONBLOCKING);
-    return ioctl(fd, FIONBIO, &state);
-#endif /* !USE_FIONBIO */
-}
 
 /*
  * Used to pad structures at size'd boundaries
@@ -82,10 +51,22 @@ TclUnixSetBlockingMode(
 
 typedef struct ThreadSpecificData {
     struct passwd pwd;
+#if defined(HAVE_GETPWNAM_R_5) || defined(HAVE_GETPWUID_R_5)
+#define NEED_PW_CLEANER 1
+    char *pbuf;
+    int pbuflen;
+#else
     char pbuf[2048];
+#endif
 
     struct group grp;
+#if defined(HAVE_GETGRNAM_R_5) || defined(HAVE_GETGRGID_R_5)
+#define NEED_GR_CLEANER 1
+    char *gbuf;
+    int gbuflen;
+#else
     char gbuf[2048];
+#endif
 
 #if !defined(HAVE_MTSAFE_GETHOSTBYNAME) || !defined(HAVE_MTSAFE_GETHOSTBYADDR)
     struct hostent hent;
@@ -124,14 +105,57 @@ static int		CopyGrp(struct group *tgtPtr, char *buf, int buflen);
 static int		CopyHostent(struct hostent *tgtPtr, char *buf,
 			    int buflen);
 static int		CopyPwd(struct passwd *tgtPtr, char *buf, int buflen);
-static int		CopyString(CONST char *src, char *buf, int buflen);
+static int		CopyString(const char *src, char *buf, int buflen);
 
 #endif
+
+#ifdef NEED_PW_CLEANER
+static void		FreePwBuf(ClientData ignored);
+#endif
+#ifdef NEED_GR_CLEANER
+static void		FreeGrBuf(ClientData ignored);
+#endif
 #endif /* TCL_THREADS */
 
 /*
  *---------------------------------------------------------------------------
  *
+ * TclUnixSetBlockingMode --
+ *
+ *	Set the blocking mode of a file descriptor.
+ *
+ * Results:
+ *
+ *	0 on success, -1 (with errno set) on error.
+ *
+ *---------------------------------------------------------------------------
+ */
+
+int
+TclUnixSetBlockingMode(
+    int fd,			/* File descriptor */
+    int mode)			/* Either TCL_MODE_BLOCKING or
+				 * TCL_MODE_NONBLOCKING. */
+{
+#ifndef USE_FIONBIO
+    int flags = fcntl(fd, F_GETFL);
+
+    if (mode == TCL_MODE_BLOCKING) {
+	flags &= ~O_NONBLOCK;
+    } else {
+	flags |= O_NONBLOCK;
+    }
+    return fcntl(fd, F_SETFL, flags);
+#else /* USE_FIONBIO */
+    int state = (mode == TCL_MODE_NONBLOCKING);
+
+    return ioctl(fd, FIONBIO, &state);
+#endif /* !USE_FIONBIO */
+}
+
+/*
+ *---------------------------------------------------------------------------
+ *
  * TclpGetPwNam --
  *
  *      Thread-safe wrappers for getpwnam(). See "man getpwnam" for more
@@ -158,8 +182,33 @@ TclpGetPwNam(
 #if defined(HAVE_GETPWNAM_R_5)
     struct passwd *pwPtr = NULL;
 
-    return (getpwnam_r(name, &tsdPtr->pwd, tsdPtr->pbuf, sizeof(tsdPtr->pbuf),
-		       &pwPtr) == 0 && pwPtr != NULL) ? &tsdPtr->pwd : NULL;
+    /*
+     * How to allocate a buffer of the right initial size. If you want the
+     * gory detail, see http://www.opengroup.org/austin/docs/austin_328.txt
+     * and weep.
+     */
+
+    if (tsdPtr->pbuf == NULL) {
+	tsdPtr->pbuflen = (int) sysconf(_SC_GETPW_R_SIZE_MAX);
+	if (tsdPtr->pbuflen < 1) {
+	    tsdPtr->pbuflen = 1024;
+	}
+	tsdPtr->pbuf = ckalloc(tsdPtr->pbuflen);
+	Tcl_CreateThreadExitHandler(FreePwBuf, NULL);
+    }
+    while (1) {
+	int e = getpwnam_r(name, &tsdPtr->pwd, tsdPtr->pbuf, tsdPtr->pbuflen,
+		&pwPtr);
+
+	if (e == 0) {
+	    break;
+	} else if (e != ERANGE) {
+	    return NULL;
+	}
+	tsdPtr->pbuflen *= 2;
+	tsdPtr->pbuf = ckrealloc(tsdPtr->pbuf, tsdPtr->pbuflen);
+    }
+    return (pwPtr != NULL ? &tsdPtr->pwd : NULL);
 
 #elif defined(HAVE_GETPWNAM_R_4)
     return getpwnam_r(name, &tsdPtr->pwd, tsdPtr->pbuf, sizeof(tsdPtr->pbuf));
@@ -214,8 +263,33 @@ TclpGetPwUid(
 #if defined(HAVE_GETPWUID_R_5)
     struct passwd *pwPtr = NULL;
 
-    return (getpwuid_r(uid, &tsdPtr->pwd, tsdPtr->pbuf, sizeof(tsdPtr->pbuf),
-		       &pwPtr) == 0 && pwPtr != NULL) ? &tsdPtr->pwd : NULL;
+    /*
+     * How to allocate a buffer of the right initial size. If you want the
+     * gory detail, see http://www.opengroup.org/austin/docs/austin_328.txt
+     * and weep.
+     */
+
+    if (tsdPtr->pbuf == NULL) {
+	tsdPtr->pbuflen = (int) sysconf(_SC_GETPW_R_SIZE_MAX);
+	if (tsdPtr->pbuflen < 1) {
+	    tsdPtr->pbuflen = 1024;
+	}
+	tsdPtr->pbuf = ckalloc(tsdPtr->pbuflen);
+	Tcl_CreateThreadExitHandler(FreePwBuf, NULL);
+    }
+    while (1) {
+	int e = getpwuid_r(uid, &tsdPtr->pwd, tsdPtr->pbuf, tsdPtr->pbuflen,
+		&pwPtr);
+
+	if (e == 0) {
+	    break;
+	} else if (e != ERANGE) {
+	    return NULL;
+	}
+	tsdPtr->pbuflen *= 2;
+	tsdPtr->pbuf = ckrealloc(tsdPtr->pbuf, tsdPtr->pbuflen);
+    }
+    return (pwPtr != NULL ? &tsdPtr->pwd : NULL);
 
 #elif defined(HAVE_GETPWUID_R_4)
     return getpwuid_r(uid, &tsdPtr->pwd, tsdPtr->pbuf, sizeof(tsdPtr->pbuf));
@@ -244,6 +318,29 @@ TclpGetPwUid(
 /*
  *---------------------------------------------------------------------------
  *
+ * FreePwBuf --
+ *
+ *	Helper that is used to dispose of space allocated and referenced from
+ *	the ThreadSpecificData for user entries. (Darn that baroque POSIX
+ *	reentrant interface.)
+ *
+ *---------------------------------------------------------------------------
+ */
+
+#ifdef NEED_PW_CLEANER
+static void
+FreePwBuf(
+    ClientData ignored)
+{
+    ThreadSpecificData *tsdPtr = TCL_TSD_INIT(&dataKey);
+
+    ckfree(tsdPtr->pbuf);
+}
+#endif /* NEED_PW_CLEANER */
+
+/*
+ *---------------------------------------------------------------------------
+ *
  * TclpGetGrNam --
  *
  *      Thread-safe wrappers for getgrnam(). See "man getgrnam" for more
@@ -267,11 +364,36 @@ TclpGetGrNam(
 #else
     ThreadSpecificData *tsdPtr = TCL_TSD_INIT(&dataKey);
 
-#if defined(HAVE_GETGRNAM_R_5)
+#ifdef HAVE_GETGRNAM_R_5
     struct group *grPtr = NULL;
 
-    return (getgrnam_r(name, &tsdPtr->grp, tsdPtr->gbuf, sizeof(tsdPtr->gbuf),
-		       &grPtr) == 0 && grPtr != NULL) ? &tsdPtr->grp : NULL;
+    /*
+     * How to allocate a buffer of the right initial size. If you want the
+     * gory detail, see http://www.opengroup.org/austin/docs/austin_328.txt
+     * and weep.
+     */
+
+    if (tsdPtr->gbuf == NULL) {
+	tsdPtr->gbuflen = (int) sysconf(_SC_GETGR_R_SIZE_MAX);
+	if (tsdPtr->gbuflen < 1) {
+	    tsdPtr->gbuflen = 1024;
+	}
+	tsdPtr->gbuf = ckalloc(tsdPtr->gbuflen);
+	Tcl_CreateThreadExitHandler(FreeGrBuf, NULL);
+    }
+    while (1) {
+	int e = getgrnam_r(name, &tsdPtr->grp, tsdPtr->gbuf, tsdPtr->gbuflen,
+		&grPtr);
+
+	if (e == 0) {
+	    break;
+	} else if (e != ERANGE) {
+	    return NULL;
+	}
+	tsdPtr->gbuflen *= 2;
+	tsdPtr->gbuf = ckrealloc(tsdPtr->gbuf, tsdPtr->gbuflen);
+    }
+    return (grPtr != NULL ? &tsdPtr->grp : NULL);
 
 #elif defined(HAVE_GETGRNAM_R_4)
     return getgrnam_r(name, &tsdPtr->grp, tsdPtr->gbuf, sizeof(tsdPtr->gbuf));
@@ -326,8 +448,33 @@ TclpGetGrGid(
 #if defined(HAVE_GETGRGID_R_5)
     struct group *grPtr = NULL;
 
-    return (getgrgid_r(gid, &tsdPtr->grp, tsdPtr->gbuf, sizeof(tsdPtr->gbuf),
-		       &grPtr) == 0 && grPtr != NULL) ? &tsdPtr->grp : NULL;
+    /*
+     * How to allocate a buffer of the right initial size. If you want the
+     * gory detail, see http://www.opengroup.org/austin/docs/austin_328.txt
+     * and weep.
+     */
+
+    if (tsdPtr->gbuf == NULL) {
+	tsdPtr->gbuflen = (int) sysconf(_SC_GETGR_R_SIZE_MAX);
+	if (tsdPtr->gbuflen < 1) {
+	    tsdPtr->gbuflen = 1024;
+	}
+	tsdPtr->gbuf = ckalloc(tsdPtr->gbuflen);
+	Tcl_CreateThreadExitHandler(FreeGrBuf, NULL);
+    }
+    while (1) {
+	int e = getgrgid_r(gid, &tsdPtr->grp, tsdPtr->gbuf, tsdPtr->gbuflen,
+		&grPtr);
+
+	if (e == 0) {
+	    break;
+	} else if (e != ERANGE) {
+	    return NULL;
+	}
+	tsdPtr->gbuflen *= 2;
+	tsdPtr->gbuf = ckrealloc(tsdPtr->gbuf, tsdPtr->gbuflen);
+    }
+    return (grPtr != NULL ? &tsdPtr->grp : NULL);
 
 #elif defined(HAVE_GETGRGID_R_4)
     return getgrgid_r(gid, &tsdPtr->grp, tsdPtr->gbuf, sizeof(tsdPtr->gbuf));
@@ -356,6 +503,29 @@ TclpGetGrGid(
 /*
  *---------------------------------------------------------------------------
  *
+ * FreeGrBuf --
+ *
+ *	Helper that is used to dispose of space allocated and referenced from
+ *	the ThreadSpecificData for group entries. (Darn that baroque POSIX
+ *	reentrant interface.)
+ *
+ *---------------------------------------------------------------------------
+ */
+
+#ifdef NEED_GR_CLEANER
+static void
+FreeGrBuf(
+    ClientData ignored)
+{
+    ThreadSpecificData *tsdPtr = TCL_TSD_INIT(&dataKey);
+
+    ckfree(tsdPtr->gbuf);
+}
+#endif /* NEED_GR_CLEANER */
+
+/*
+ *---------------------------------------------------------------------------
+ *
  * TclpGetHostByName --
  *
  *      Thread-safe wrappers for gethostbyname(). See "man gethostbyname" for
@@ -769,7 +939,7 @@ CopyArray(
 #ifdef NEED_COPYSTRING
 static int
 CopyString(
-    CONST char *src,	/* String to copy. */
+    const char *src,		/* String to copy. */
     char *buf,			/* Buffer to copy into. */
     int buflen)			/* Size of buffer. */
 {
@@ -788,14 +958,6 @@ CopyString(
 #endif /* NEED_COPYSTRING */
 
 /*
- * Local Variables:
- * mode: c
- * c-basic-offset: 4
- * fill-column: 78
- * End:
- */
-
-/*
  *------------------------------------------------------------------------
  *
  * TclWinCPUID --
@@ -831,7 +993,7 @@ TclWinCPUID(
 #endif
     return status;
 }
-
+
 /*
  * Local Variables:
  * mode: c