Util (Linux): add elf helper

Author: CarterLi

CMakeLists.txt

@@ -69,6 +69,7 @@ cmake_dependent_option(ENABLE_FREETYPE "Enable freetype" ON "ANDROID" OFF)
 cmake_dependent_option(ENABLE_PULSE "Enable pulse" ON "LINUX OR SunOS" OFF)
 cmake_dependent_option(ENABLE_DDCUTIL "Enable ddcutil" ON "LINUX" OFF)
 cmake_dependent_option(ENABLE_DIRECTX_HEADERS "Enable DirectX headers for WSL" ON "LINUX" OFF)
+cmake_dependent_option(ENABLE_ELF "Enable libelf" ON "LINUX" OFF)
 cmake_dependent_option(ENABLE_THREADS "Enable multithreading" ON "Threads_FOUND" OFF)
 
 option(ENABLE_SYSTEM_YYJSON "Use system provided (instead of fastfetch embedded) yyjson library" OFF)
@@ -480,6 +481,7 @@ if(LINUX)
         src/detection/wmtheme/wmtheme_linux.c
         src/detection/camera/camera_linux.c
         src/util/platform/FFPlatform_unix.c
+        src/util/linux/elf.c
     )
 elseif(ANDROID)
     list(APPEND LIBFASTFETCH_SRC
@@ -1075,6 +1077,10 @@ ff_lib_enable(DDCUTIL
     "ddcutil"
     "Ddcutil"
 )
+ff_lib_enable(ELF
+    "libelf"
+    "libelf"
+)
 ff_lib_enable(DIRECTX_HEADERS
     "DirectX-Headers"
     "DirectX-Headers"

doc/json_schema.json

@@ -730,6 +730,10 @@
                 "ddcutil": {
                     "description": "Used for brightness detection of external displays (Linux)",
                     "type": "string"
+                },
+                "elf": {
+                    "description": "Used for st terminal font detection and systemd version detection (Linux)",
+                    "type": "string"
                 }
             }
         },

src/common/init.c

@@ -248,6 +248,9 @@ void ffListFeatures(void)
         #if FF_HAVE_DDCUTIL
             "libddcutil\n"
         #endif
+        #if FF_HAVE_ELF
+            "libelf\n"
+        #endif
         #if FF_HAVE_DIRECTX_HEADERS
             "Directx Headers\n"
         #endif

src/data/help.json

@@ -935,6 +935,13 @@
             "arg": {
                 "type": "path"
             }
+        },
+        {
+            "long": "lib-elf",
+            "desc": "Used for st terminal font detection and systemd version detection",
+            "arg": {
+                "type": "path"
+            }
         }
     ],
     "Module specific": [

src/options/library.c

@@ -66,6 +66,8 @@ const char* ffOptionsParseLibraryJsonConfig(FFOptionsLibrary* options, yyjson_va
             ffStrbufSetS(&options->libDdcutil, yyjson_get_str(val));
         else if (ffStrEqualsIgnCase(key, "drm"))
             ffStrbufSetS(&options->libdrm, yyjson_get_str(val));
+        else if (ffStrEqualsIgnCase(key, "elf"))
+            ffStrbufSetS(&options->libelf, yyjson_get_str(val));
 #endif
 
         else
@@ -131,6 +133,8 @@ bool ffOptionsParseLibraryCommandLine(FFOptionsLibrary* options, const char* key
             ffOptionParseString(key, value, &options->libDdcutil);
         else if(ffStrEqualsIgnCase(subkey, "drm"))
             ffOptionParseString(key, value, &options->libdrm);
+        else if(ffStrEqualsIgnCase(subkey, "elf"))
+            ffOptionParseString(key, value, &options->libelf);
 #endif
 
         else

src/options/library.h

@@ -32,6 +32,7 @@ typedef struct FFOptionsLibrary
     FFstrbuf libPulse;
     FFstrbuf libDdcutil;
     FFstrbuf libdrm;
+    FFstrbuf libelf;
 #endif
 } FFOptionsLibrary;
 

src/util/linux/elf.c

@@ -0,0 +1,85 @@
+#include "elf.h"
+
+#ifdef FF_HAVE_ELF
+
+#include "common/io/io.h"
+#include "common/library.h"
+#include "util/stringUtils.h"
+
+#include <libelf.h>
+#include <fcntl.h>
+
+const char* ffElfExtractStrings(const char* elfFile, bool (*cb)(const char* str, uint32_t len, void* userdata), void* userdata)
+{
+    FF_LIBRARY_LOAD(libelf, &instance.config.library.libelf, "dlopen libelf" FF_LIBRARY_EXTENSION " failed", "libelf" FF_LIBRARY_EXTENSION, 1);
+    FF_LIBRARY_LOAD_SYMBOL_MESSAGE(libelf, elf_version)
+    FF_LIBRARY_LOAD_SYMBOL_MESSAGE(libelf, elf_begin)
+    FF_LIBRARY_LOAD_SYMBOL_MESSAGE(libelf, elf_getshdrstrndx)
+    FF_LIBRARY_LOAD_SYMBOL_MESSAGE(libelf, elf_nextscn)
+    FF_LIBRARY_LOAD_SYMBOL_MESSAGE(libelf, elf64_getshdr)
+    FF_LIBRARY_LOAD_SYMBOL_MESSAGE(libelf, elf32_getshdr)
+    FF_LIBRARY_LOAD_SYMBOL_MESSAGE(libelf, elf_getdata)
+    FF_LIBRARY_LOAD_SYMBOL_MESSAGE(libelf, elf_strptr)
+    FF_LIBRARY_LOAD_SYMBOL_MESSAGE(libelf, elf_end)
+
+    if (ffelf_version(EV_CURRENT) == EV_NONE) return "elf_version() failed";
+
+    FF_AUTO_CLOSE_FD int fd = open(elfFile, O_RDONLY, 0);
+    if (fd < 0) return "open() failed";
+
+    Elf* elf = ffelf_begin(fd, ELF_C_READ, NULL);
+    if (elf == NULL) return "elf_begin() failed";
+
+    size_t shstrndx = 0;
+    if (ffelf_getshdrstrndx(elf, &shstrndx) < 0)
+    {
+        ffelf_end(elf);
+        return "elf_getshdrstrndx() failed";
+    }
+
+    Elf_Scn* scn = NULL;
+    FF_STRBUF_AUTO_DESTROY buffer = ffStrbufCreate();
+    while ((scn = ffelf_nextscn(elf, scn)) != NULL)
+    {
+        Elf64_Shdr* shdr64 = ffelf64_getshdr(scn);
+        Elf32_Shdr* shdr32 = NULL;
+        if (shdr64 == NULL)
+        {
+            shdr32 = ffelf32_getshdr(scn);
+            if (shdr32 == NULL) continue;
+        }
+
+        const char* name = ffelf_strptr(elf, shstrndx, shdr64 ? shdr64->sh_name : shdr32->sh_name);
+        if (name == NULL || !ffStrEquals(name, ".rodata")) continue;
+
+        Elf_Data* data = ffelf_getdata(scn, NULL);
+        if (data == NULL) continue;
+
+        for (size_t off = 0; off < data->d_size; ++off)
+        {
+            const char* p = (const char*) data->d_buf + off;
+            if (*p == '\0') continue;
+            uint32_t len = (uint32_t) strlen(p);
+            if (*p >= ' ' && *p <= '~') // Ignore control characters
+            {
+                if (!cb(p, len, userdata)) break;
+            }
+            off += len;
+        }
+
+        break;
+    }
+
+    ffelf_end(elf);
+    return NULL;
+}
+
+#else
+
+const char* ffElfExtractStrings(const char* elfFile, bool (*cb)(const char* str, uint32_t len, void* userdata), void* userdata)
+{
+    FF_UNUSED(elfFile, cb, userdata);
+    return "Fastfetch was built without libelf support";
+}
+
+#endif

src/util/linux/elf.h

@@ -0,0 +1,5 @@
+#pragma once
+
+#include "fastfetch.h"
+
+const char* ffElfExtractStrings(const char* elfFile, bool (*cb)(const char* str, uint32_t len, void* userdata), void* userdata);