From 61b2bbe3eb265861265c1cf928e156e3c7052721 Mon Sep 17 00:00:00 2001
From: Ralph Ronnquist <ralph.ronnquist@gmail.com>
Date: Wed, 26 Oct 2022 14:33:06 +1100
Subject: [PATCH] debugging

---
 libtarmap-0.c | 43 ++++++++++++++++++++++++++++++-------------
 1 file changed, 30 insertions(+), 13 deletions(-)

diff --git a/libtarmap-0.c b/libtarmap-0.c
index 89c0f4a..8625616 100644
--- a/libtarmap-0.c
+++ b/libtarmap-0.c
@@ -69,9 +69,11 @@ static FILE *tryopentar(const char *pathname) {
 
 // Override "openat"
 int openat(int dirfd, const char *pathname, int flags) {
-    static int (*real_openat)(int, const char*, int);
-    if ( real_openat == 0 ) {
-	real_openat = dlsym( libc6, "openat" );
+    static int (*real_openat)(int, const char*, int) = 0;
+    if ( libc6 == 0 ) {
+	void *lib = dlopen( "libc.so.6", RTLD_LAZY );
+	real_openat = dlsym( lib, "openat" );
+	return real_openat( dirfd, pathname, flags );
     }
     //fprintf( stderr, "openat( %s )\n", pathname );
     if ( data.tarmap ) {
@@ -85,9 +87,11 @@ int openat(int dirfd, const char *pathname, int flags) {
 
 // Override "open"
 int open(const char *pathname, int flags) {
-    static int (*real_open)(const char *pathname, int flags);
-    if ( real_open == 0 ) {
-	real_open = dlsym( libc6, "open" );
+    static int (*real_open)(const char *pathname, int flags) = 0;
+    if ( libc6 == 0 ) {
+	void *lib = dlopen( "libc.so.6", RTLD_LAZY );
+	real_open = dlsym( lib, "open" );
+	return real_open( pathname, flags );
     }
     //fprintf( stderr, "open( %s )\n", pathname );
     if ( data.tarmap ) {
@@ -101,9 +105,11 @@ int open(const char *pathname, int flags) {
 
 // Override "fopen"
 FILE *fopen(const char *pathname, const char *mode) {
-    static FILE *(*real_fopen)(const char *pathname, const char *mode);
+    static FILE *(*real_fopen)(const char *pathname, const char *mode) = 0;
     if ( real_fopen == 0 ) {
-	real_fopen = dlsym( libc6, "fopen" );
+	void *lib = dlopen( "libc.so.6", RTLD_LAZY );
+	real_fopen = dlsym( lib, "fopen" );
+	return real_fopen( pathname, mode );
     }
     if ( data.tarmap ) {
 	FILE *file = tryopentar( pathname );
@@ -121,14 +127,17 @@ void so_init() {
     if ( libc6 ) {
 	return;
     }
-    libc6 = dlopen( "libc.so.6", RTLD_LAZY );
     char *tarfile = getenv( TARMAP );
     if ( tarfile == 0 || *tarfile == 0 ) {
 	//fprintf( stderr, "(libtarmap: no tar)\n" );
 	data.tarmap = 0;
 	return; // Stop here for unset or cleared environment
     }
-    //fprintf( stderr, "libtarmap: tarfile = %s\n", tarfile );
+    //fprintf( stderr, "libtarmap: %s\n", tarfile? tarfile : "(null)" );
+    libc6 = dlopen( "libc.so.6", RTLD_LAZY );
+    real_openat = dlsym( libc6, "openat" );
+    real_open = dlsym( libc6, "open" );
+    real_fopen = dlsym( libc6, "fopen" );
     if ( ( data.tarmap = realpath( tarfile, 0 ) ) == 0 ) {
 	// Cannot find the tar file .. that's total badness!
 	perror( tarfile );
@@ -142,8 +151,17 @@ void so_init() {
 	perror( data.tarmap );
 	exit( 1 );
     }
+    int fd = fileno( file );
     data.buffer = malloc( DATASZ );
-    data.size = read( fileno( file ), data.buffer, DATASZ );
+    char *p = data.buffer;
+    int max = DATASZ;
+    int n;
+    while ( ( n = read( fd, p, max ) ) > 0 ) {
+	data.size += n;
+	p += n;
+	max -= n;
+    }
+    //fprintf( stderr, "data.size = %d\n", data.size );
     if ( data.size == 0 ) {
 	perror( cmd );
 	// Not a tar or empty tar .. that's total badness!
@@ -160,8 +178,7 @@ void so_init() {
     free( cmd );
     cmd = 0;
     char *end = data.buffer + data.size;
-    char *p;
-    int n = 0;
+    n = 0;
     for ( p = data.buffer; p < end; p++ ) {
 	if ( *p == '\n' ) {
 	    n++;
-- 
2.47.2