cc: support versioned SONAME in shared library resolution

bcc_procutils_which_so() and related helpers previously handled only
short library names (e.g. "ssl"), constructing "lib%s.so" and selecting
the first cache entry from /etc/ld.so.cache.

This change makes to recognize versioned SONAME fragments that contain
".so.x" (e.g. "ssl.so.3.5.3", "crypto.so.3"), treating such names as
exact matches instead of appending another ".so". This enables correct
resolution of versioned libraries (e.g. libssl.so.3 vs libssl.so.59)
while maintaining compatibility with existing short-name lookups.

This improves correctness on systems where multiple SONAME variants
coexist in the cache (e.g. OpenSSL vs LibreSSL).

Related: #5412

Signed-off-by: Hoyeon Lee <[email protected]>

Author: HoyeonRhee

docs/reference_guide.md

@@ -1723,7 +1723,7 @@ By default `pid` is set to -1, indicating the `uprobe` will be attached to all p
 For libraries, the uprobe will attach to the version of the library used by the process if `pid` was given.
 For how `pid` is used, see examples in [funcinterval](https://github.com/iovisor/bcc/blob/78423e1667db202012bbb032c567589175a2796c/tools/funcinterval.py#L155-L156).
 
-Libraries can be given in the name argument without the lib prefix, or with the full path (/usr/lib/...). Binaries can be given only with the full path (/bin/sh).
+Libraries can be given in the name argument without the lib prefix, optionally with a versioned SONAME (c.so.6), or with the full path (/usr/lib/...). Binaries can be given only with the full path (/bin/sh).
 
 For example:
 

src/cc/bcc_proc.c

@@ -469,7 +469,8 @@ static bool which_so_in_process(const char* libname, int pid, char* libpath) {
   int ret, found = false;
   char endline[4096], *mapname = NULL, *newline;
   char mappings_file[128];
-  const size_t search_len = strlen(libname) + strlen("/lib.");
+  const bool has_so = strstr(libname, ".so");
+  const size_t search_len = strlen(libname) + strlen(has_so ? "/lib" : "/lib.");
   char search1[search_len + 1];
   char search2[search_len + 1];
 
@@ -478,8 +479,13 @@ static bool which_so_in_process(const char* libname, int pid, char* libpath) {
   if (!fp)
     return NULL;
 
-  snprintf(search1, search_len + 1, "/lib%s.", libname);
-  snprintf(search2, search_len + 1, "/lib%s-", libname);
+  if (has_so) {
+    snprintf(search1, search_len + 1, "/lib%s", libname);
+    search2[0] = '\0';
+  } else {
+    snprintf(search1, search_len + 1, "/lib%s.", libname);
+    snprintf(search2, search_len + 1, "/lib%s-", libname);
+  }
 
   do {
     ret = fscanf(fp, "%*x-%*x %*s %*x %*s %*d");
@@ -494,7 +500,7 @@ static bool which_so_in_process(const char* libname, int pid, char* libpath) {
     while (isspace(mapname[0])) mapname++;
 
     if (strstr(mapname, ".so") && (strstr(mapname, search1) ||
-                                   strstr(mapname, search2))) {
+                                   (!has_so && strstr(mapname, search2)))) {
       const size_t mapnamelen = strlen(mapname);
       if (mapnamelen >= PATH_MAX) {
         fprintf(stderr, "Found mapped library path is too long\n");
@@ -511,7 +517,8 @@ static bool which_so_in_process(const char* libname, int pid, char* libpath) {
 }
 
 static bool which_so_in_ldconfig_cache(const char* libname, char* libpath) {
-  const size_t soname_len = strlen(libname) + strlen("lib.so");
+  const bool has_so = strstr(libname, ".so");
+  const size_t soname_len = strlen(libname) + strlen(has_so ? "lib" : "lib.so");
   char soname[soname_len + 1];
   int i;
 
@@ -523,7 +530,7 @@ static bool which_so_in_ldconfig_cache(const char* libname, char* libpath) {
     return false;
   }
 
-  snprintf(soname, soname_len + 1, "lib%s.so", libname);
+  snprintf(soname, sizeof(soname), has_so ? "lib%s" : "lib%s.so", libname);
 
   for (i = 0; i < lib_cache_count; ++i) {
     if (!strncmp(lib_cache[i].libname, soname, soname_len) &&