78134b0ccd
strtoull() can optionally take a second pointer as an out-parameter that will be adjusted to point to the end of the parsed string. This works almost right, but misses two important edge cases: firstly,when the parsed string is "0", the function will interpret the leading '0' as an octal prefix, so that the first actually parsed digit is already the terminating '\0' byte. This will cause the function to early abort, which still (correctly) returns 0 but doesn't adjust *endptr. The early abort is pointless anyway -- the only other thing the function does is run a for-loop whose condition is the exact inverse (so it's guaranteed to run zero iterations in this case) and then adjust *endptr (which we want). So just take it out. This also technically corrects the behavior of *endptr for a completely invalid string, since the strtoull man page says > If there were no digits at all, strtoul() stores the original value of > nptr in *endptr (and returns 0). The second issue occurs when the parsed string is "0x" without another valid digit behind it. In this case, we will still jump over the 0x prefix so that *endptr is set to the first byte after that. The correct interpretation in this case is that there is no 0x prefix, and instead a valid 0 digit with the 'x' being invalid garbage at the end. By not skipping the prefix unless there's at least one valid digit after it, we get the correct behavior of *endptr pointing to the 'x'. Change-Id: Idddd74e18e410a9d0b6dce9512ca0412b9e2333c Signed-off-by: Julius Werner <jwerner@chromium.org> Reviewed-on: https://review.coreboot.org/c/coreboot/+/32029 Tested-by: build bot (Jenkins) <no-reply@coreboot.org> Reviewed-by: Nico Huber <nico.h@gmx.de> Reviewed-by: Paul Menzel <paulepanter@users.sourceforge.net> |
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|---|---|---|
| .. | ||
| arch | ||
| bin | ||
| configs | ||
| crypto | ||
| curses | ||
| drivers | ||
| gdb | ||
| include | ||
| libc | ||
| libcbfs | ||
| liblz4 | ||
| liblzma | ||
| libpci | ||
| sample | ||
| tests | ||
| Doxyfile | ||
| Kconfig | ||
| LICENSES | ||
| LICENSE_GPL | ||
| Makefile | ||
| Makefile.inc | ||
| README | ||
README
-------------------------------------------------------------------------------
libpayload README
-------------------------------------------------------------------------------
libpayload is a minimal library to support standalone payloads
that can be booted with firmware like coreboot. It handles the setup
code, and provides common C library symbols such as malloc() and printf().
Note: This is _not_ a standard library for use with an operating system,
rather it's only useful for coreboot payload development!
See https://www.coreboot.org for details on coreboot.
Installation
------------
$ git clone https://review.coreboot.org/coreboot.git
$ cd coreboot/payloads/libpayload
$ make menuconfig
$ make
$ sudo make install (optional, will install into /opt per default)
As libpayload is for 32bit x86 systems only, you might have to install the
32bit libgcc version, otherwise your payloads will fail to compile.
On Debian systems you'd do 'apt-get install gcc-multilib' for example.
Usage
-----
Here's an example of a very simple payload (hello.c) and how to build it:
#include <libpayload.h>
int main(void)
{
printf("Hello, world!\n");
return 0;
}
Building the payload using the 'lpgcc' compiler wrapper:
$ lpgcc -o hello.elf hello.c
Please see the sample/ directory for details.
Website and Mailing List
------------------------
The main website is https://www.coreboot.org/Libpayload.
For additional information, patches, and discussions, please join the
coreboot mailing list at https://www.coreboot.org/Mailinglist, where most
libpayload developers are subscribed.
Copyright and License
---------------------
See LICENSES.