changeset 9abf6a7c14ab in /z/repo/gem5
details: http://repo.gem5.org/gem5?cmd=changeset;node=9abf6a7c14ab
description:
syscall: Add readlink to x86 with special case /proc/self/exe
This patch implements the correct behavior.
diffstat:
src/arch/x86/linux/process.cc | 6 +++---
src/sim/syscall_emul.cc | 31 ++++++++++++++++++++++++++-----
2 files changed, 29 insertions(+), 8 deletions(-)
diffs (80 lines):
diff -r 255ebb0b32b4 -r 9abf6a7c14ab src/arch/x86/linux/process.cc
--- a/src/arch/x86/linux/process.cc Mon Jul 20 09:15:18 2015 -0500
+++ b/src/arch/x86/linux/process.cc Mon Jul 20 09:15:18 2015 -0500
@@ -485,7 +485,7 @@
/* 264 */ SyscallDesc("renameat", unimplementedFunc),
/* 265 */ SyscallDesc("linkat", unimplementedFunc),
/* 266 */ SyscallDesc("symlinkat", unimplementedFunc),
- /* 267 */ SyscallDesc("readlinkat", unimplementedFunc),
+ /* 267 */ SyscallDesc("readlinkat", readlinkFunc),
/* 268 */ SyscallDesc("fchmodat", unimplementedFunc),
/* 269 */ SyscallDesc("faccessat", unimplementedFunc),
/* 270 */ SyscallDesc("pselect6", unimplementedFunc),
@@ -626,7 +626,7 @@
/* 82 */ SyscallDesc("select", unimplementedFunc),
/* 83 */ SyscallDesc("symlink", unimplementedFunc),
/* 84 */ SyscallDesc("oldlstat", unimplementedFunc),
- /* 85 */ SyscallDesc("readlink", unimplementedFunc),
+ /* 85 */ SyscallDesc("readlink", readlinkFunc),
/* 86 */ SyscallDesc("uselib", unimplementedFunc),
/* 87 */ SyscallDesc("swapon", unimplementedFunc),
/* 88 */ SyscallDesc("reboot", unimplementedFunc),
@@ -846,7 +846,7 @@
/* 302 */ SyscallDesc("renameat", unimplementedFunc),
/* 303 */ SyscallDesc("linkat", unimplementedFunc),
/* 304 */ SyscallDesc("symlinkat", unimplementedFunc),
- /* 305 */ SyscallDesc("readlinkat", unimplementedFunc),
+ /* 305 */ SyscallDesc("readlinkat", readlinkFunc),
/* 306 */ SyscallDesc("fchmodat", unimplementedFunc),
/* 307 */ SyscallDesc("faccessat", unimplementedFunc),
/* 308 */ SyscallDesc("pselect6", unimplementedFunc),
diff -r 255ebb0b32b4 -r 9abf6a7c14ab src/sim/syscall_emul.cc
--- a/src/sim/syscall_emul.cc Mon Jul 20 09:15:18 2015 -0500
+++ b/src/sim/syscall_emul.cc Mon Jul 20 09:15:18 2015 -0500
@@ -365,12 +365,10 @@
}
strncpy((char *)buf.bufferPtr(), cwd.c_str(), size);
result = cwd.length();
- }
- else {
+ } else {
if (getcwd((char *)buf.bufferPtr(), size) != NULL) {
result = strlen((char *)buf.bufferPtr());
- }
- else {
+ } else {
result = -1;
}
}
@@ -405,7 +403,30 @@
BufferArg buf(bufPtr, bufsiz);
- int result = readlink(path.c_str(), (char *)buf.bufferPtr(), bufsiz);
+ int result = -1;
+ if (path != "/proc/self/exe") {
+ result = readlink(path.c_str(), (char *)buf.bufferPtr(), bufsiz);
+ } else {
+ // readlink() will return the path of the binary given
+ // with the -c option, however it is possible that this
+ // will still result in incorrect behavior if one binary
+ // runs another, e.g., -c time -o "my_binary" where
+ // my_binary calls readlink(). this is a very unlikely case,
+ // so we issue a warning.
+ warn_once("readlink may yield unexpected results if multiple "
+ "binaries are used\n");
+ if (strlen(p->progName()) > bufsiz) {
+ // readlink will truncate the contents of the
+ // path to ensure it is no more than bufsiz
+ strncpy((char*)buf.bufferPtr(), p->progName(), bufsiz);
+ result = bufsiz;
+ } else {
+ // return the program's working path rather
+ // than the one for the gem5 binary itself.
+ strcpy((char*)buf.bufferPtr(), p->progName());
+ result = strlen((char*)buf.bufferPtr());
+ }
+ }
buf.copyOut(tc->getMemProxy());
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