Assert the existence of original functions

The friendly folks at #musl again: 21:17 < dalias> if you init the pointers both from the ctor and the "lazy init", then the assertion-failure/abort would happen during construction (either your ctor or somebody else's ctor calling your functions) 21:17 < dalias> so the program would exit "before it even gets started" 21:17 < dalias> and this is not so bad 21:18 < dalias> normally i consider it really bad practice for a library to abort the program 21:18 < dalias> but this happens during ctors, and there truely is no way to proceed 21:18 < dalias> if you've already replaced the program's library functions (open, etc.) with your copies, and then find that you can't actually supply working ones

Assert the existence of original functions
e979b3dd · Julius Plenz · 1a36b32e · e979b3dd
Commit e979b3dd authored May 20, 2013 by Julius Plenz
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nocache.c nocache.c +12 -0

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--- a/nocache.c
+++ b/nocache.c
@@ -157,6 +157,7 @@ int open(const char *pathname, int flags, mode_t mode)

    if(!_original_open)
        _original_open = (int (*)(const char *, int, mode_t)) dlsym(RTLD_NEXT, "open");
+    assert(_original_open != NULL);

    if((fd = _original_open(pathname, flags, mode)) != -1)
        store_pageinfo(fd);
@@ -169,6 +170,7 @@ int open64(const char *pathname, int flags, mode_t mode)

    if(!_original_open64)
        _original_open64 = (int (*)(const char *, int, mode_t)) dlsym(RTLD_NEXT, "open64");
+    assert(_original_open64 != NULL);

    if((fd = _original_open64(pathname, flags, mode)) != -1)
        store_pageinfo(fd);
@@ -181,6 +183,7 @@ int creat(const char *pathname, int flags, mode_t mode)

    if(!_original_creat)
        _original_creat = (int (*)(const char *, int, mode_t)) dlsym(RTLD_NEXT, "creat");
+    assert(_original_creat != NULL);

    if((fd = _original_creat(pathname, flags, mode)) != -1)
        store_pageinfo(fd);
@@ -193,6 +196,7 @@ int creat64(const char *pathname, int flags, mode_t mode)

    if(!_original_creat64)
        _original_creat64 = (int (*)(const char *, int, mode_t)) dlsym(RTLD_NEXT, "creat64");
+    assert(_original_creat64 != NULL);

    if((fd = _original_creat64(pathname, flags, mode)) != -1)
        store_pageinfo(fd);
@@ -205,6 +209,7 @@ int openat(int dirfd, const char *pathname, int flags, mode_t mode)

    if(!_original_openat)
        _original_openat = (int (*)(int, const char *, int, mode_t)) dlsym(RTLD_NEXT, "openat");
+    assert(_original_openat != NULL);

    if((fd = _original_openat(dirfd, pathname, flags, mode)) != -1)
        store_pageinfo(fd);
@@ -217,6 +222,7 @@ int openat64(int dirfd, const char *pathname, int flags, mode_t mode)

    if(!_original_openat64)
        _original_openat64 = (int (*)(int, const char *, int, mode_t)) dlsym(RTLD_NEXT, "openat64");
+    assert(_original_openat64 != NULL);

    if((fd = _original_openat64(dirfd, pathname, flags, mode)) != -1)
        store_pageinfo(fd);
@@ -229,6 +235,7 @@ int dup(int oldfd)

    if(!_original_dup)
        _original_dup = (int (*)(int)) dlsym(RTLD_NEXT, "dup");
+    assert(_original_dup != NULL);

    if((fd = _original_dup(oldfd)) != -1)
        store_pageinfo(fd);
@@ -247,6 +254,7 @@ int dup2(int oldfd, int newfd)

    if(!_original_dup2)
        _original_dup2 = (int (*)(int, int)) dlsym(RTLD_NEXT, "dup2");
+    assert(_original_dup2 != NULL);

    if((ret = _original_dup2(oldfd, newfd)) != -1)
        store_pageinfo(newfd);
@@ -257,6 +265,7 @@ int close(int fd)
 {
    if(!_original_close)
        _original_close = (int (*)(int)) dlsym(RTLD_NEXT, "close");
+    assert(_original_close != NULL);

    free_unclaimed_pages(fd);
    return _original_close(fd);
@@ -269,6 +278,7 @@ FILE *fopen(const char *path, const char *mode)

    if(!_original_fopen)
       _original_fopen = (FILE *(*)(const char *, const char *)) dlsym(RTLD_NEXT, "fopen");
+    assert(_original_fopen != NULL);

    if((fp = _original_fopen(path, mode)) != NULL)
        if((fd = fileno(fp)) != -1)
@@ -285,6 +295,7 @@ FILE *fopen64(const char *path, const char *mode)

    if(!_original_fopen64)
        _original_fopen64 = (FILE *(*)(const char *, const char *)) dlsym(RTLD_NEXT, "fopen64");
+    assert(_original_fopen64 != NULL);

    if((fp = _original_fopen64(path, mode)) != NULL)
        if((fd = fileno(fp)) != -1)
@@ -297,6 +308,7 @@ int fclose(FILE *fp)
 {
    if(!_original_fclose)
        _original_fclose = (int (*)(FILE *)) dlsym(RTLD_NEXT, "fclose");
+    assert(_original_fclose != NULL);

    if(_original_fclose) {
        free_unclaimed_pages(fileno(fp));