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std: start code on linux when -lc also expands stack size

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See #8708
This commit is contained in:
Andrew Kelley 2021-05-07 21:34:53 -07:00
parent f69cf93064
commit 6ec24a6502
1 changed files with 38 additions and 27 deletions
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65
lib/std/start.zig
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@ -302,8 +302,8 @@ fn posixCallMainAndExit() noreturn {
// no, seriously, give me that stack space, I wasn't joking.
{
var i: usize = 0;
var at_phnum: usize = undefined;
var at_phdr: usize = undefined;
var at_phnum: usize = undefined;
while (auxv[i].a_type != std.elf.AT_NULL) : (i += 1) {
switch (auxv[i].a_type) {
std.elf.AT_PHNUM => at_phnum = auxv[i].a_un.a_val,
@ -311,38 +311,42 @@ fn posixCallMainAndExit() noreturn {
else => continue,
}
}
const phdrs = (@intToPtr([*]std.elf.Phdr, at_phdr))[0..at_phnum];
for (phdrs) |*phdr| {
switch (phdr.p_type) {
std.elf.PT_GNU_STACK => {
const wanted_stack_size = phdr.p_memsz;
assert(wanted_stack_size % std.mem.page_size == 0);
std.os.setrlimit(.STACK, .{
.cur = wanted_stack_size,
.max = wanted_stack_size,
}) catch {
// If this is a debug build, it will be useful to find out
// why this failed. If it is a release build, we allow the
// stack overflow to cause a segmentation fault. Memory safety
// is not compromised, however, depending on runtime state,
// the application may crash due to provided stack space not
// matching the known upper bound.
if (builtin.mode == .Debug) {
@panic("unable to increase stack size");
}
};
break;
},
else => {},
}
}
expandStackSize(at_phdr, at_phnum);
}
}
std.os.exit(@call(.{ .modifier = .always_inline }, callMainWithArgs, .{ argc, argv, envp }));
}
fn expandStackSize(at_phdr: usize, at_phnum: usize) void {
const phdrs = (@intToPtr([*]std.elf.Phdr, at_phdr))[0..at_phnum];
for (phdrs) |*phdr| {
switch (phdr.p_type) {
std.elf.PT_GNU_STACK => {
const wanted_stack_size = phdr.p_memsz;
assert(wanted_stack_size % std.mem.page_size == 0);
std.os.setrlimit(.STACK, .{
.cur = wanted_stack_size,
.max = wanted_stack_size,
}) catch {
// If this is a debug build, it will be useful to find out
// why this failed. If it is a release build, we allow the
// stack overflow to cause a segmentation fault. Memory safety
// is not compromised, however, depending on runtime state,
// the application may crash due to provided stack space not
// matching the known upper bound.
if (builtin.mode == .Debug) {
@panic("unable to increase stack size");
}
};
break;
},
else => {},
}
}
}
fn callMainWithArgs(argc: usize, argv: [*][*:0]u8, envp: [][*:0]u8) u8 {
std.os.argv = argv[0..argc];
std.os.environ = envp;
@ -356,6 +360,13 @@ fn main(c_argc: i32, c_argv: [*][*:0]u8, c_envp: [*:null]?[*:0]u8) callconv(.C)
var env_count: usize = 0;
while (c_envp[env_count] != null) : (env_count += 1) {}
const envp = @ptrCast([*][*:0]u8, c_envp)[0..env_count];
if (builtin.os.tag == .linux) {
const at_phdr = std.c.getauxval(std.elf.AT_PHDR);
const at_phnum = std.c.getauxval(std.elf.AT_PHNUM);
expandStackSize(at_phdr, at_phnum);
}
return @call(.{ .modifier = .always_inline }, callMainWithArgs, .{ @intCast(usize, c_argc), c_argv, envp });
}