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[Valgrind-developers] [valgrind] Darwin: add only necessary env vars
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From: Paul F. <pa...@so...> - 2026-03-20 21:18:19
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https://sourceware.org/cgit/valgrind/commit/?id=d560275826ec38823607316562e9be1a4c3bfb8b commit d560275826ec38823607316562e9be1a4c3bfb8b Author: Paul Floyd <pj...@wa...> Date: Fri Mar 20 22:03:14 2026 +0100 Darwin: add only necessary env vars We were always adding DYLD_SHARED_REGION. On macOS 11+ this isn't necessary and we can just leave dyld do its thing. If we don't add it we don't need to remove it either. Diff: --- coregrind/m_initimg/initimg-darwin.c | 82 ++++++++++++++++++++++++++++-------- coregrind/vg_preloaded.c | 6 +++ 2 files changed, 70 insertions(+), 18 deletions(-) diff --git a/coregrind/m_initimg/initimg-darwin.c b/coregrind/m_initimg/initimg-darwin.c index b65ab4f5a9..773e6da643 100644 --- a/coregrind/m_initimg/initimg-darwin.c +++ b/coregrind/m_initimg/initimg-darwin.c @@ -131,13 +131,28 @@ static void load_client ( /*OUT*/ExeInfo* info, Also, remove any binding for VALGRIND_LAUNCHER=. The client should not be able to see this. - Before macOS 11: - Also, add DYLD_SHARED_REGION=avoid, because V doesn't know how - to process the dyld shared cache file. + There are up to three other environment variables that we need to + add or modify. - Since macOS 11: - Use DYLD_SHARED_REGION=use because system libraries aren't provided outside the cache anymore. - This means we need to start processing the dyld shared cache file. + PTHREAD_PTR_MUNGE_TOKEN: This is used by libc/libpthread to obfuscate + some saved context registers. + FIXME PJF - if we correctly propagate the apple parameter ptr_munge + would we still need this env var? + + DYLD_SHARED_REGION: Darwin switched to dematerialising system libraries. + On some versions of Darwin this environment variable can be used + with a value of 'avoid' to force using the physical libraries on disk. + Later versions removed the physical library files so we can + no longer use this option with 'avoid' and we need to start processing + the dyld shared cache file. + + DYLD_INSERT_LIBRARIES: V uses this to preload its core and tool + shared libraries. + + The following macOS versions have the following requirements + All versions: DYLD_INSERT_LIBRARIES + DARWIN_VERS >= DARWIN_10_15 PTHREAD_PTR_MUNGE_TOKEN + DARWIN_VERS < DARWIN_11_00 DYLD_SHARED_REGION Also, change VYLD_* (mangled by launcher) back to DYLD_*. @@ -148,18 +163,20 @@ static HChar** setup_client_env ( HChar** origenv, const HChar* toolname) { const HChar* preload_core = "vgpreload_core"; const HChar* ld_preload = "DYLD_INSERT_LIBRARIES="; +#if DARWIN_VERS < DARWIN_11_00 const HChar* dyld_cache = "DYLD_SHARED_REGION="; -#if DARWIN_VERS >= DARWIN_11_00 - const HChar* dyld_cache_value= "use"; -#else const HChar* dyld_cache_value= "avoid"; + Int dyld_cache_len = VG_(strlen)( dyld_cache ); + Bool dyld_cache_done = False; +#endif +#if DARWIN_VERS >= DARWIN_10_15 + Bool pthread_ptr_munge_token_present = False; #endif const HChar* v_launcher = VALGRIND_LAUNCHER "="; + Int extra_env_vars; Int ld_preload_len = VG_(strlen)( ld_preload ); - Int dyld_cache_len = VG_(strlen)( dyld_cache ); Int v_launcher_len = VG_(strlen)( v_launcher ); Bool ld_preload_done = False; - Bool dyld_cache_done = False; Int vglib_len = VG_(strlen)(VG_(libdir)); HChar** cpp; @@ -167,6 +184,15 @@ static HChar** setup_client_env ( HChar** origenv, const HChar* toolname) HChar* preload_tool_path; Int envc, i; + // number of env vars to add if not already present +#if DARWIN_VERS < DARWIN_10_15 + extra_env_vars = 2; // DYLD_INSERT_LIBRARIES and DYLD_SHARED_REGION +#elif DARWIN_VERS == DARWIN_10_15 + extra_env_vars = 3; // DYLD_INSERT_LIBRARIES, DYLD_SHARED_REGION and PTHREAD_PTR_MUNGE_TOKEN +#else // > DARWIN_10_15 + extra_env_vars = 2; // DYLD_INSERT_LIBRARIES and PTHREAD_PTR_MUNGE_TOKEN +#endif + /* Alloc space for the vgpreload_core.so path and vgpreload_<tool>.so paths. We might not need the space for vgpreload_<tool>.so, but it doesn't hurt to over-allocate briefly. The 16s are just cautious @@ -197,16 +223,30 @@ static HChar** setup_client_env ( HChar** origenv, const HChar* toolname) /* Count the original size of the env */ envc = 0; - for (cpp = origenv; cpp && *cpp; cpp++) + for (cpp = origenv; cpp && *cpp; cpp++) { + if (VG_(memcmp)(*cpp, ld_preload, ld_preload_len) == 0) { + --extra_env_vars; + } +#if DARWIN_VERS < DARWIN_11_00 + if (VG_(memcmp)(*cpp, dyld_cache, dyld_cache_len) == 0) { + --extra_env_vars; + } +#endif +#if DARWIN_VERS >= DARWIN_10_15 + // strictly would should check for presence and that it is not set to zero + if (VG_(memcmp)(*cpp, "PTHREAD_PTR_MUNGE_TOKEN=", VG_(strlen)("PTHREAD_PTR_MUNGE_TOKEN=")) == 0) { + --extra_env_vars; + pthread_ptr_munge_token_present = True; + } +#endif envc++; + } + + vg_assert(extra_env_vars >= 0); /* Allocate a new space */ ret = VG_(malloc) ("initimg-darwin.sce.3", -#if DARWIN_VERS >= DARWIN_10_15 - sizeof(HChar *) * (envc+3+1)); /* 3 new entries + NULL */ -#else - sizeof(HChar *) * (envc+2+1)); /* 2 new entries + NULL */ -#endif + sizeof(HChar *) * (envc+extra_env_vars+1)); /* 1 to 3 new entries + NULL */ /* copy it over */ for (cpp = ret; *origenv; ) @@ -228,6 +268,7 @@ static HChar** setup_client_env ( HChar** origenv, const HChar* toolname) ld_preload_done = True; } +#if DARWIN_VERS < DARWIN_11_00 if (VG_(memcmp)(*cpp, dyld_cache, dyld_cache_len) == 0) { Int len = dyld_cache_len + VG_(strlen)(dyld_cache_value) + 1; HChar *cp = VG_(malloc)("initimg-darwin.sce.4.2", len); @@ -238,6 +279,7 @@ static HChar** setup_client_env ( HChar** origenv, const HChar* toolname) dyld_cache_done = True; } +#endif } /* Add the missing bits */ @@ -249,6 +291,7 @@ static HChar** setup_client_env ( HChar** origenv, const HChar* toolname) ret[envc++] = cp; } +#if DARWIN_VERS < DARWIN_11_00 if (!dyld_cache_done) { Int len = dyld_cache_len + VG_(strlen)(dyld_cache_value) + 1; HChar *cp = VG_(malloc) ("initimg-darwin.sce.5.2", len); @@ -257,9 +300,12 @@ static HChar** setup_client_env ( HChar** origenv, const HChar* toolname) ret[envc++] = cp; } +#endif #if DARWIN_VERS >= DARWIN_10_15 // pthread really wants a non-zero value for ptr_munge - ret[envc++] = VG_(strdup)("initimg-darwin.sce.6", "PTHREAD_PTR_MUNGE_TOKEN=0x00000001"); + if (!pthread_ptr_munge_token_present) { + ret[envc++] = VG_(strdup)("initimg-darwin.sce.6", "PTHREAD_PTR_MUNGE_TOKEN=0x00000001"); + } #endif /* ret[0 .. envc-1] is live now. */ diff --git a/coregrind/vg_preloaded.c b/coregrind/vg_preloaded.c index 4da57aa95a..4215382705 100644 --- a/coregrind/vg_preloaded.c +++ b/coregrind/vg_preloaded.c @@ -244,13 +244,19 @@ static void env_unsetenv ( HChar **env, const HChar *varname ) #endif } +// FIXME PJF to we really need this? +// We already do env cleanup before any exec static void vg_cleanup_env(void) __attribute__((constructor)); static void vg_cleanup_env(void) { HChar **envp = (HChar**)*_NSGetEnviron(); +#if DARWIN_VERS < DARWIN_11_00 env_unsetenv(envp, "DYLD_SHARED_REGION"); +#endif // GrP fixme should be more like mash_colon_env() env_unsetenv(envp, "DYLD_INSERT_LIBRARIES"); + // FIXME PJF on macOS >= 10.15 we also insert PTHREAD_PTR_MUNGE_TOKEN + // should we remove it here? } /* --------------------------------------------------------------------- |
