diff --git a/cfg/posix.cfg b/cfg/posix.cfg
index 6beea8182..87f242951 100644
--- a/cfg/posix.cfg
+++ b/cfg/posix.cfg
@@ -4,6 +4,7 @@
   <!-- long a64l(const char *str64); -->
   <function name="a64l">
     <use-retval/>
+    <returnValue type="long"/>
     <noreturn>false</noreturn>
     <leak-ignore/>
     <arg nr="1">
@@ -15,6 +16,7 @@
   <!-- char *l64a(long value); -->
   <function name="l64a">
     <use-retval/>
+    <returnValue type="char *"/>
     <noreturn>false</noreturn>
     <leak-ignore/>
     <arg nr="1">
@@ -29,6 +31,7 @@
   <function name="accept">
     <noreturn>false</noreturn>
     <leak-ignore/>
+    <returnValue type="int"/>
     <arg nr="1">
       <not-uninit/>
     </arg>
@@ -43,6 +46,7 @@
   <!-- int access(const char *pathname, int amode); -->
   <function name="access">
     <use-retval/>
+    <returnValue type="int"/>
     <noreturn>false</noreturn>
     <leak-ignore/>
     <arg nr="1">
@@ -58,6 +62,7 @@
   <function name="adjtime">
     <noreturn>false</noreturn>
     <leak-ignore/>
+    <returnValue type="int"/>
     <arg nr="1">
       <not-uninit/>
     </arg>
@@ -84,6 +89,7 @@
   <!-- int gettimeofday(struct timeval *tv, struct timezone *tz); -->
   <function name="gettimeofday">
     <noreturn>false</noreturn>
+    <returnValue type="int"/>
     <leak-ignore/>
     <arg nr="1"/>
     <arg nr="2"/>
@@ -91,6 +97,7 @@
   <!-- int settimeofday(const struct timeval *tv, const struct timezone *tz); -->
   <function name="settimeofday">
     <noreturn>false</noreturn>
+    <returnValue type="int"/>
     <leak-ignore/>
     <arg nr="1">
       <not-uninit/>
@@ -110,10 +117,11 @@
       <not-null/>
     </arg>
   </function>
-  <!-- int  FD_ISSET(int fd, fd_set *set); -->
+  <!-- int FD_ISSET(int fd, fd_set *set); -->
   <function name="FD_ISSET">
     <noreturn>false</noreturn>
     <leak-ignore/>
+    <returnValue type="int"/>
     <arg nr="1">
       <not-uninit/>
     </arg>
@@ -145,6 +153,7 @@
   <function name="fdatasync">
     <noreturn>false</noreturn>
     <leak-ignore/>
+    <returnValue type="int"/>
     <arg nr="1">
       <not-uninit/>
     </arg>
@@ -154,6 +163,7 @@
   <function name="fnmatch">
     <pure/>
     <use-retval/>
+    <returnValue type="int"/>
     <noreturn>false</noreturn>
     <leak-ignore/>
     <arg nr="1">
@@ -173,6 +183,7 @@
   <function name="fsync">
     <noreturn>false</noreturn>
     <leak-ignore/>
+    <returnValue type="int"/>
     <arg nr="1">
       <not-uninit/>
     </arg>
@@ -181,6 +192,7 @@
   <function name="truncate">
     <noreturn>false</noreturn>
     <leak-ignore/>
+    <returnValue type="int"/>
     <arg nr="1">
       <not-null/>
       <not-uninit/>
@@ -193,6 +205,7 @@
   <function name="ftruncate">
     <noreturn>false</noreturn>
     <leak-ignore/>
+    <returnValue type="int"/>
     <arg nr="1">
       <not-uninit/>
     </arg>
@@ -204,6 +217,7 @@
   <function name="flock">
     <noreturn>false</noreturn>
     <leak-ignore/>
+    <returnValue type="int"/>
     <arg nr="1">
       <not-uninit/>
     </arg>
@@ -215,6 +229,7 @@
   <function name="symlink">
     <noreturn>false</noreturn>
     <leak-ignore/>
+    <returnValue type="int"/>
     <arg nr="1">
       <not-null/>
       <not-uninit/>
@@ -227,6 +242,7 @@
   <!-- int open(const char *pathname, int flags) -->
   <function name="open">
     <use-retval/>
+    <returnValue type="int"/>
     <noreturn>false</noreturn>
     <arg nr="1">
       <not-null/>
@@ -239,6 +255,7 @@
   <!-- int open(const char *pathname, int flags, mode_t mode); -->
   <function name="open">
     <use-retval/>
+    <returnValue type="int"/>
     <noreturn>false</noreturn>
     <arg nr="1">
       <not-null/>
@@ -254,6 +271,7 @@
   <!-- int creat(const char *pathname, mode_t mode); -->
   <function name="creat">
     <use-retval/>
+    <returnValue type="int"/>
     <noreturn>false</noreturn>
     <arg nr="1">
       <not-null/>
@@ -267,6 +285,7 @@
   <function name="sleep">
     <noreturn>false</noreturn>
     <leak-ignore/>
+    <returnValue type="unsigned int"/>
     <arg nr="1">
       <not-uninit/>
       <not-bool/>
@@ -276,6 +295,7 @@
   <!-- int usleep(useconds_t useconds); -->
   <function name="usleep">
     <noreturn>false</noreturn>
+    <returnValue type="int"/>
     <leak-ignore/>
     <arg nr="1">
       <not-bool/>
@@ -296,6 +316,7 @@ The obsolescent function 'usleep' is called. POSIX.1-2001 declares usleep() func
   <function name="access">
     <noreturn>false</noreturn>
     <leak-ignore/>
+    <returnValue type="int"/>
     <arg nr="1">
       <not-null/>
       <not-uninit/>
@@ -309,6 +330,7 @@ The obsolescent function 'usleep' is called. POSIX.1-2001 declares usleep() func
   <function name="faccessat">
     <noreturn>false</noreturn>
     <leak-ignore/>
+    <returnValue type="int"/>
     <arg nr="1">
       <not-uninit/>
     </arg>
@@ -328,6 +350,7 @@ The obsolescent function 'usleep' is called. POSIX.1-2001 declares usleep() func
   <function name="acct">
     <noreturn>false</noreturn>
     <leak-ignore/>
+    <returnValue type="int"/>
     <arg nr="1">
       <not-uninit/>
     </arg>
@@ -337,6 +360,7 @@ The obsolescent function 'usleep' is called. POSIX.1-2001 declares usleep() func
   <function name="alarm">
     <noreturn>false</noreturn>
     <leak-ignore/>
+    <returnValue type="unsigned int"/>
     <arg nr="1">
       <not-uninit/>
       <valid>0:</valid>
@@ -516,6 +540,7 @@ The obsolescent function 'usleep' is called. POSIX.1-2001 declares usleep() func
   <function name="brk">
     <noreturn>false</noreturn>
     <leak-ignore/>
+    <returnValue type="int"/>
     <arg nr="1">
       <not-null/>
     </arg>
@@ -531,6 +556,7 @@ The obsolescent function 'usleep' is called. POSIX.1-2001 declares usleep() func
   <!-- int closedir(DIR *dir); -->
   <function name="closedir">
     <noreturn>false</noreturn>
+    <returnValue type="int"/>
     <arg nr="1">
       <not-null/>
       <not-uninit/>
@@ -540,6 +566,7 @@ The obsolescent function 'usleep' is called. POSIX.1-2001 declares usleep() func
   <!-- char *strfry(char *string); -->
   <function name="strfry">
     <noreturn>false</noreturn>
+    <returnValue type="char *"/>
     <arg nr="1">
       <not-null/>
     </arg>
@@ -548,6 +575,7 @@ The obsolescent function 'usleep' is called. POSIX.1-2001 declares usleep() func
   <function name="strsep">
     <noreturn>false</noreturn>
     <leak-ignore/>
+    <returnValue type="char *"/>
     <arg nr="1">
       <not-uninit/>
       <not-null/>
@@ -560,6 +588,7 @@ The obsolescent function 'usleep' is called. POSIX.1-2001 declares usleep() func
   <!-- char *strdup(const char *s); -->
   <function name="strdup">
     <noreturn>false</noreturn>
+    <returnValue type="char *"/>
     <arg nr="1">
       <not-null/>
       <not-uninit/>
@@ -568,6 +597,7 @@ The obsolescent function 'usleep' is called. POSIX.1-2001 declares usleep() func
   <!-- char *strndup(const char *s, size_t n); -->
   <function name="strndup">
     <noreturn>false</noreturn>
+    <returnValue type="char *"/>
     <arg nr="1">
       <not-null/>
       <not-uninit/>
@@ -580,6 +610,7 @@ The obsolescent function 'usleep' is called. POSIX.1-2001 declares usleep() func
   <!-- wchar_t *wcsdup(const wchar_t *s); -->
   <function name="wcsdup">
     <noreturn>false</noreturn>
+    <returnValue type="wchar_t *"/>
     <arg nr="1">
       <not-null/>
       <not-uninit/>
@@ -589,6 +620,7 @@ The obsolescent function 'usleep' is called. POSIX.1-2001 declares usleep() func
   <function name="mkstemp">
     <noreturn>false</noreturn>
     <leak-ignore/>
+    <returnValue type="int"/>
     <arg nr="1">
       <not-null/>
       <not-uninit/>
@@ -598,6 +630,7 @@ The obsolescent function 'usleep' is called. POSIX.1-2001 declares usleep() func
   <function name="mkdtemp">
     <noreturn>false</noreturn>
     <leak-ignore/>
+    <returnValue type="char *"/>
     <arg nr="1">
       <not-null/>
       <not-uninit/>
@@ -606,6 +639,7 @@ The obsolescent function 'usleep' is called. POSIX.1-2001 declares usleep() func
   <!-- char *mktemp(char *template); -->
   <function name="mktemp">
     <noreturn>false</noreturn>
+    <returnValue type="char *"/>
     <leak-ignore/>
     <use-retval/>
     <arg nr="1">
@@ -618,6 +652,7 @@ The function 'mktemp' is considered to be dangerous due to race conditions and s
   <!-- char *getcwd(char *buf, size_t size); -->
   <function name="getcwd">
     <noreturn>false</noreturn>
+    <returnValue type="char *"/>
     <leak-ignore/>
     <arg nr="1">
       <not-uninit/>
@@ -630,6 +665,7 @@ The function 'mktemp' is considered to be dangerous due to race conditions and s
   <!-- int mkdir(const char *pathname, mode_t mode); -->
   <function name="mkdir">
     <noreturn>false</noreturn>
+    <returnValue type="int"/>
     <leak-ignore/>
     <arg nr="1">
       <not-null/>
@@ -643,6 +679,7 @@ The function 'mktemp' is considered to be dangerous due to race conditions and s
   <function name="rmdir">
     <noreturn>false</noreturn>
     <leak-ignore/>
+    <returnValue type="int"/>
     <arg nr="1">
       <not-null/>
       <not-uninit/>
@@ -652,6 +689,7 @@ The function 'mktemp' is considered to be dangerous due to race conditions and s
   <function name="chdir">
     <noreturn>false</noreturn>
     <leak-ignore/>
+    <returnValue type="int"/>
     <arg nr="1">
       <not-null/>
       <not-uninit/>
@@ -661,6 +699,7 @@ The function 'mktemp' is considered to be dangerous due to race conditions and s
   <function name="chroot">
     <noreturn>false</noreturn>
     <leak-ignore/>
+    <returnValue type="int"/>
     <arg nr="1">
       <not-null/>
       <not-uninit/>
@@ -670,6 +709,7 @@ The function 'mktemp' is considered to be dangerous due to race conditions and s
   <function name="link">
     <noreturn>false</noreturn>
     <leak-ignore/>
+    <returnValue type="int"/>
     <arg nr="1">
       <not-null/>
       <not-uninit/>
@@ -683,6 +723,7 @@ The function 'mktemp' is considered to be dangerous due to race conditions and s
   <function name="unlink">
     <noreturn>false</noreturn>
     <leak-ignore/>
+    <returnValue type="int"/>
     <arg nr="1">
       <not-null/>
       <not-uninit/>
@@ -692,6 +733,7 @@ The function 'mktemp' is considered to be dangerous due to race conditions and s
   <function name="rename">
     <noreturn>false</noreturn>
     <leak-ignore/>
+    <returnValue type="int"/>
     <arg nr="1">
       <not-null/>
       <not-uninit/>
@@ -701,6 +743,7 @@ The function 'mktemp' is considered to be dangerous due to race conditions and s
   <function name="stat">
     <noreturn>false</noreturn>
     <leak-ignore/>
+    <returnValue type="int"/>
     <arg nr="1">
       <not-null/>
       <not-uninit/>
@@ -713,6 +756,7 @@ The function 'mktemp' is considered to be dangerous due to race conditions and s
   <function name="lstat">
     <noreturn>false</noreturn>
     <leak-ignore/>
+    <returnValue type="int"/>
     <arg nr="1">
       <not-null/>
       <not-uninit/>
@@ -725,6 +769,7 @@ The function 'mktemp' is considered to be dangerous due to race conditions and s
   <function name="fstat">
     <noreturn>false</noreturn>
     <leak-ignore/>
+    <returnValue type="int"/>
     <arg nr="1">
       <not-uninit/>
     </arg>
@@ -736,6 +781,7 @@ The function 'mktemp' is considered to be dangerous due to race conditions and s
   <function name="chmod">
     <noreturn>false</noreturn>
     <leak-ignore/>
+    <returnValue type="int"/>
     <arg nr="1">
       <not-null/>
       <not-uninit/>
@@ -748,6 +794,7 @@ The function 'mktemp' is considered to be dangerous due to race conditions and s
   <function name="fchmod">
     <noreturn>false</noreturn>
     <leak-ignore/>
+    <returnValue type="int"/>
     <arg nr="1">
       <not-uninit/>
     </arg>
@@ -759,6 +806,7 @@ The function 'mktemp' is considered to be dangerous due to race conditions and s
   <function name="chown">
     <noreturn>false</noreturn>
     <leak-ignore/>
+    <returnValue type="int"/>
     <arg nr="1">
       <not-null/>
       <not-uninit/>
@@ -774,6 +822,7 @@ The function 'mktemp' is considered to be dangerous due to race conditions and s
   <function name="lchown">
     <noreturn>false</noreturn>
     <leak-ignore/>
+    <returnValue type="int"/>
     <arg nr="1">
       <not-null/>
       <not-uninit/>
@@ -789,6 +838,7 @@ The function 'mktemp' is considered to be dangerous due to race conditions and s
   <function name="fchown">
     <noreturn>false</noreturn>
     <leak-ignore/>
+    <returnValue type="int"/>
     <arg nr="1">
       <not-uninit/>
     </arg>
@@ -810,6 +860,7 @@ The function 'mktemp' is considered to be dangerous due to race conditions and s
   <function name="utime">
     <noreturn>false</noreturn>
     <leak-ignore/>
+    <returnValue type="int"/>
     <arg nr="1">
       <not-null/>
       <not-uninit/>
@@ -823,6 +874,7 @@ The function 'mktemp' is considered to be dangerous due to race conditions and s
   <function name="utimes">
     <noreturn>false</noreturn>
     <leak-ignore/>
+    <returnValue type="int"/>
     <arg nr="1">
       <not-null/>
       <not-uninit/>
@@ -850,6 +902,7 @@ The function 'mktemp' is considered to be dangerous due to race conditions and s
   <!-- int isatty(int fildes); -->
   <function name="isatty">
     <use-retval/>
+    <returnValue type="int"/>
     <noreturn>false</noreturn>
     <leak-ignore/>
     <arg nr="1">
@@ -871,6 +924,7 @@ The function 'mktemp' is considered to be dangerous due to race conditions and s
   </function>
   <!-- int pclose(FILE *stream); -->
   <function name="pclose">
+    <returnValue type="int"/>
     <noreturn>false</noreturn>
     <arg nr="1">
       <not-null/>
@@ -880,6 +934,7 @@ The function 'mktemp' is considered to be dangerous due to race conditions and s
   <!-- int socket(int domain, int type, int protocol); -->
   <function name="socket">
     <noreturn>false</noreturn>
+    <returnValue type="int"/>
     <arg nr="1">
       <not-uninit/>
     </arg>
@@ -893,6 +948,7 @@ The function 'mktemp' is considered to be dangerous due to race conditions and s
   <!-- int nice(int incr); -->
   <function name="nice">
     <noreturn>false</noreturn>
+    <returnValue type="int"/>
     <leak-ignore/>
     <arg nr="1">
       <not-uninit/>
@@ -901,11 +957,13 @@ The function 'mktemp' is considered to be dangerous due to race conditions and s
   <!-- int pause(void); -->
   <function name="pause">
     <noreturn>false</noreturn>
+    <returnValue type="int"/>
     <leak-ignore/>
   </function>
   <!-- int close(int fildes); -->
   <function name="close">
     <noreturn>false</noreturn>
+    <returnValue type="int"/>
     <arg nr="1">
       <not-uninit/>
     </arg>
@@ -914,6 +972,7 @@ The function 'mktemp' is considered to be dangerous due to race conditions and s
   <function name="confstr">
     <noreturn>false</noreturn>
     <leak-ignore/>
+    <returnValue type="size_t"/>
     <arg nr="1">
       <not-uninit/>
     </arg>
@@ -929,6 +988,7 @@ The function 'mktemp' is considered to be dangerous due to race conditions and s
   <function name="fpathconf">
     <noreturn>false</noreturn>
     <leak-ignore/>
+    <returnValue type="long int"/>
     <arg nr="1">
       <not-uninit/>
     </arg>
@@ -940,6 +1000,7 @@ The function 'mktemp' is considered to be dangerous due to race conditions and s
   <function name="pathconf">
     <noreturn>false</noreturn>
     <leak-ignore/>
+    <returnValue type="long int"/>
     <arg nr="1">
       <not-null/>
       <not-uninit/>
@@ -952,6 +1013,7 @@ The function 'mktemp' is considered to be dangerous due to race conditions and s
   <function name="sysconf">
     <noreturn>false</noreturn>
     <leak-ignore/>
+    <returnValue type="long int"/>
     <arg nr="1">
       <not-uninit/>
     </arg>
@@ -971,6 +1033,7 @@ The function 'mktemp' is considered to be dangerous due to race conditions and s
   <!-- long int random(void); -->
   <function name="random">
     <use-retval/>
+    <returnValue type="long int"/>
     <noreturn>false</noreturn>
   </function>
   <!-- void srandom(unsigned int seed); -->
@@ -1015,6 +1078,7 @@ The function 'mktemp' is considered to be dangerous due to race conditions and s
   <function name="rand_r">
     <noreturn>false</noreturn>
     <leak-ignore/>
+    <returnValue type="int"/>
     <arg nr="1">
       <not-null/>
     </arg>
@@ -1025,6 +1089,7 @@ The function 'mktemp' is considered to be dangerous due to race conditions and s
     <pure/>
     <noreturn>false</noreturn>
     <leak-ignore/>
+    <returnValue type="int"/>
     <arg nr="1">
       <not-null/>
       <not-uninit/>
@@ -1039,6 +1104,7 @@ The function 'mktemp' is considered to be dangerous due to race conditions and s
     <pure/>
     <noreturn>false</noreturn>
     <leak-ignore/>
+    <returnValue type="int"/>
     <arg nr="1">
       <not-null/>
       <not-uninit/>