From 2ab7e303527d002293f4307b02fdff521d3c1e61 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?J=C5=8Dshin?= <git@wholezero.org>
Date: Tue, 7 May 2024 15:45:32 -0700
Subject: [PATCH] Use a less common flag for ape

We choose 0x101ca75, "lol cat 5".

Also makes the argc check more explicit and moves the flags to their own
section.
---
 ape/ape-m1.c   | 6 ++++--
 ape/ape.S      | 4 ++--
 ape/loader.c   | 6 ++++--
 libc/elf/def.h | 3 ++-
 4 files changed, 12 insertions(+), 7 deletions(-)

diff --git a/ape/ape-m1.c b/ape/ape-m1.c
index 9912adefc..8d188404a 100644
--- a/ape/ape-m1.c
+++ b/ape/ape-m1.c
@@ -124,7 +124,6 @@ struct Syslib {
 #define PT_INTERP                   3
 #define EI_CLASS                    4
 #define EI_DATA                     5
-#define EF_APE_MODERN               1
 #define PF_X                        1
 #define PF_W                        2
 #define PF_R                        4
@@ -147,6 +146,9 @@ struct Syslib {
 #define AT_RANDOM                   25
 #define AT_EXECFN                   31
 
+#define EF_APE_MODERN      0x101ca75
+#define EF_APE_MODERN_MASK 0x1ffffff
+
 #define AUXV_WORDS 31
 
 /* from the xnu codebase */
@@ -821,7 +823,7 @@ static const char *TryElf(struct ApeLoader *M, union ElfEhdrBuf *ebuf,
   if (e->e_machine != EM_AARCH64) {
     return "couldn't find ELF header with ARM64 machine type";
   }
-  if (!(e->e_flags & EF_APE_MODERN) && sp[0]) {
+  if ((e->e_flags & EF_APE_MODERN_MASK) != EF_APE_MODERN && sp[0] > 0) {
     /* change argv[0] to resolved path for older binaries */
     ((char **)(sp + 1))[0] = exe;
   }
diff --git a/ape/ape.S b/ape/ape.S
index ad1ae1b74..98d093268 100644
--- a/ape/ape.S
+++ b/ape/ape.S
@@ -196,7 +196,7 @@ ape_mz:
 	.quad	ape_elf_entry			//  18: e_entry
 	.quad	ape_elf_phoff			//  20: e_phoff
 	.quad	ape_elf_shoff			//  28: e_shoff
-	.long	1				//  30: e_flags
+	.long	0x101ca75			//  30: ape e_flags
 	.short	64				//  34: e_ehsize
 	.short	56				//  36: e_phentsize
 	.short	ape_elf_phnum			//  38: e_phnum
@@ -669,7 +669,7 @@ apesh:	.ascii	"\n@\n#'\"\n"			// sixth edition shebang
 	.shstub	    ape_elf_entry,8		//  18: e_entry
 	.shstub	    ape_elf_phoff,8		//  20: e_phoff
 	.shstub	    ape_elf_shoff,8		//  28: e_shoff
-	.ascii	    "\\1\\0\\0\\0"		//  30: e_flags
+	.ascii	    "\\165\\312\\1\\1"		//  30: ape e_flags
 	.ascii	    "\\100\\0"			//  34: e_ehsize
 	.ascii	    "\\070\\0"			//  36: e_phentsize
 	.shstub	    ape_elf_phnum,2		//  38: e_phnum
diff --git a/ape/loader.c b/ape/loader.c
index 912db4ca2..b68493497 100644
--- a/ape/loader.c
+++ b/ape/loader.c
@@ -134,7 +134,6 @@
 #define PT_INTERP                   3
 #define EI_CLASS                    4
 #define EI_DATA                     5
-#define EF_APE_MODERN               1
 #define PF_X                        1
 #define PF_W                        2
 #define PF_R                        4
@@ -153,6 +152,9 @@
 #define PR_SET_MM                   35
 #define PR_SET_MM_EXE_FILE          13
 
+#define EF_APE_MODERN      0x101ca75
+#define EF_APE_MODERN_MASK 0x1ffffff
+
 #define READ32(S)                                                      \
   ((unsigned)(255 & (S)[3]) << 030 | (unsigned)(255 & (S)[2]) << 020 | \
    (unsigned)(255 & (S)[1]) << 010 | (unsigned)(255 & (S)[0]) << 000)
@@ -835,7 +837,7 @@ static const char *TryElf(struct ApeLoader *M, union ElfEhdrBuf *ebuf,
     return "couldn't find ELF header with x86-64 machine type";
   }
 #endif
-  if (!(e->e_flags & EF_APE_MODERN) && sp[0]) {
+  if ((e->e_flags & EF_APE_MODERN_MASK) != EF_APE_MODERN && sp[0] > 0) {
     /* change argv[0] to resolved path for older binaries */
     ((char **)(sp + 1))[0] = exe;
   }
diff --git a/libc/elf/def.h b/libc/elf/def.h
index 7cd3c2221..a322684a7 100644
--- a/libc/elf/def.h
+++ b/libc/elf/def.h
@@ -85,7 +85,8 @@
 #define EM_RISCV     243
 #define EM_BPF       247
 
-#define EF_APE_MODERN 1
+/* the ape flag, "lol cat 5" */
+#define EF_APE_MODERN 0x101ca75
 
 #define GRP_COMDAT 1
 #define STN_UNDEF  0