Add fm_realpath(): a malloc()ating realpath() wrapper.

6 files changed, 87 insertions, 9 deletions

diff --git a/Makefile.am b/Makefile.am
index 77fe40f5..2ba02438 100644
--- a/Makefile.am
+++ b/Makefile.am
@@ -47,7 +47,7 @@ DEPENDENCIES=		libfm.a $(LIBOBJS)
 
 check_PROGRAMS=
 
-TESTS=			t.smoke t.validate-xhtml10 t.validate-xhtml t.x509_name_match
+TESTS=			t.smoke t.validate-xhtml10 t.validate-xhtml t.x509_name_match t.realpath
 LOG_COMPILER=		env LC_ALL=C TZ=UTC $(SHELL)
 
 if NEED_TRIO
@@ -72,7 +72,8 @@ fetchmail_SOURCES=	fetchmail.h getopt.h \
 		unmime.c conf.c checkalias.c uid_db.h uid_db.c\
 		lock.h lock.c \
 		rcfile_l.l rcfile_y.y \
-		ucs/norm_charmap.c ucs/norm_charmap.h
+		ucs/norm_charmap.c ucs/norm_charmap.h \
+		fm_realpath.c
 if POP2_ENABLE
 fetchmail_SOURCES += pop2.c
 endif
@@ -102,7 +103,9 @@ fetchmail_SOURCES += libesmtp/getaddrinfo.h libesmtp/getaddrinfo.c
 endif
 
 check_PROGRAMS +=	rfc822 unmime netrc rfc2047e mxget rfc822valid \
-			x509_name_match
+			x509_name_match fm_realpath
+
+fm_realpath_CFLAGS=	-DTEST
 
 rfc2047e_CFLAGS=	-DTEST
 
diff --git a/README b/README
index 2e143438..c6264cde 100644
--- a/README
+++ b/README
@@ -37,7 +37,9 @@ NEXTSTEP, OSF 3.2, IRIX, and Rhapsody once upon a time.
 The current maintainer does not have access to these systems, and assumes that
 the system is at least Single-Unix-Specification V2 compatible, yet fetchmail
 should be compilable by a C89 compiler. It currently ships with a copy of the
-trio library for systems that lack snprintf().
+trio library for systems that lack snprintf(). A further requirement is that
+either realpath() permits its 2nd argument to be NULL for auto-allocation,
+or that otherwise PATH_MAX be defined.
 
 Fetchmail should be able to be compiled with C89, C99, C11, C++98, C++03,
 C++11, C++14 compilers, but not C++17 because the "register" keyword is
diff --git a/configure.ac b/configure.ac
index 2cde1ba4..6fd2caf6 100644
--- a/configure.ac
+++ b/configure.ac
@@ -3,13 +3,13 @@ dnl Autoconfigure input file for fetchmail
 # Fetchmail automatic configuration support
 #
 # Eric S. Raymond <esr@thyrsus.com>
-# 2004 - 2019 Matthias Andree <matthias.andree@gmx.de>
+# 2004 - 2020 Matthias Andree <matthias.andree@gmx.de>
 #
 dnl Process this file with autoconf to produce a configure script.
 dnl
 
 dnl XXX - if bumping version here, check fetchmail.man, too!
-AC_INIT([fetchmail],[6.4.4],[fetchmail-users@lists.sourceforge.net])
+AC_INIT([fetchmail],[6.4.5-rc1],[fetchmail-users@lists.sourceforge.net])
 AC_CONFIG_SRCDIR([fetchmail.h])
 AC_CONFIG_HEADERS([config.h])
 AC_CONFIG_LIBOBJ_DIR([.])
@@ -98,6 +98,9 @@ AC_CHECK_DECLS([h_errno],,,[
 
 AC_C_CONST			dnl getopt needs this.
 AC_C_INLINE			dnl uid_db.? need this.
+AC_C_RESTRICT			dnl fm_realpath needs this.
+AC_C_VOLATILE			dnl check for ANSI volatile
+
 
 AM_PROG_LEX
 AC_PROG_MAKE_SET
@@ -181,6 +184,7 @@ AC_CHECK_FUNCS(tcsetattr stty setsid geteuid seteuid dnl
   sigaction strdup setlocale)
 
 AC_CHECK_DECLS([strerror])
+AC_CHECK_DECLS([PATH_MAX],,,[#include <limits.h>])
 dnl INET6 is used by KAME/getnameinfo
 AC_CACHE_CHECK(for AF_INET6/PF_INET6,ac_cv_inet6,
 AC_COMPILE_IFELSE([
@@ -235,9 +239,6 @@ AC_COMPILE_IFELSE([AC_LANG_PROGRAM([[]], [[char *p;
     p = (char *) xmalloc(1);
    ]])],[AC_DEFINE(HAVE_VOIDPOINTER,1,[Define if your C compiler allows void * as a function result]) AC_MSG_RESULT(yes)],[AC_MSG_RESULT(no)])
 
-dnl Check for ANSI volatile
-AC_C_VOLATILE
-
 dnl Check out the wait reality.  We have to assume sys/wait.h is present.
 AC_CHECK_FUNCS(waitpid wait3)
 AC_MSG_CHECKING(for union wait);
diff --git a/fetchmail.h b/fetchmail.h
index f731e159..902aae18 100644
--- a/fetchmail.h
+++ b/fetchmail.h
@@ -792,4 +792,8 @@ int ntlm_helper(int sock, struct query *ctl, const char *protocol);
 	&& (run.showdots || !is_a_file(1)))
 
 #endif
+
+/* fm_realpath.c */
+char *fm_realpath(const char *restrict file_name);
+
 /* fetchmail.h ends here */
diff --git a/fm_realpath.c b/fm_realpath.c
new file mode 100644
index 00000000..5ae8ca08
--- /dev/null
+++ b/fm_realpath.c
@@ -0,0 +1,62 @@
+#include "config.h"
+#include "fetchmail.h"
+#include "i18n.h"
+
+#include <errno.h>
+#include <limits.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <unistd.h>
+
+/* similar to realpath(file_name, NULL) - on systems that do not natively 
+ * support the resolved file name to be passed as NULL, malloc() the buffer of 
+ * PATH_MAX + 1 bytes, or abort if the system does not define PATH_MAX
+ */
+char *fm_realpath(const char *restrict file_name)
+{
+	char *rv;
+
+	if (NULL == file_name) {
+		errno = EINVAL;
+		return NULL;
+	}
+
+	rv = realpath(file_name, NULL);
+		/* FreeBSD, recent GNU libc, and all SUSv4
+		 * compliant systems auto-allocate => done */
+	if (NULL == rv && errno == EINVAL) {
+		/* Implementation does not auto-allocate, but
+		 * PATH_MAX is provided (Solaris 10, f.i.) */
+#if HAVE_DECL_PATH_MAX
+		char *b = (char *)xmalloc(PATH_MAX + 1);
+		rv = realpath(file_name, b);
+#else
+		/* unsupported */
+		report(stderr, GT_("Your operating system neither defines PATH_MAX nor will it accept realpath(f, NULL). Aborting.\n"));
+		abort();
+#endif
+	}
+	return rv;
+}
+
+#ifdef TEST
+#include <string.h>
+const char *program_name= __FILE__;
+
+int main(int argc, char **argv)
+{
+	int i;
+	int e = EXIT_SUCCESS;
+	for (i = 1; i < argc; ++i) {
+		char *p = fm_realpath(argv[i]);
+		if (p) {
+			printf("%s -> %s\n", argv[i], p);
+			free(p);
+		} else {
+			fprintf(stderr, "%s: error: %s\n", argv[i], strerror(errno));
+			e = EXIT_FAILURE;
+		}
+	}
+	exit(e);
+}
+#endif
diff --git a/t.realpath b/t.realpath
new file mode 100755
index 00000000..634fc15f
--- /dev/null
+++ b/t.realpath
@@ -0,0 +1,6 @@
+#! /bin/sh
+
+# This is a rudimentary tests to check if realpath() works.
+
+set -eu
+./fm_realpath "." "$(pwd)"