strtod() should only advance *endptr one byte given "0x"

[i80and]

#include <stdio.h>
#include <stdlib.h>
int main(void) {
  const char* str = "0x";
  char* endp;
  strtod(str, &endp);
  printf("%ld\n", endp - str);
}

On other platforms, this will print 1. On Haiku, it prints 2.

From ​http://pubs.opengroup.org/onlinepubs/9699919799/functions/strtod.html:

The expected form of the subject sequence is an optional '+' or '-' sign, then one of the following: ...

• A 0x or 0X, then a non-empty sequence of hexadecimal digits...

Other platforms do not advance *endptr to indicate that the 'x' was consumed, which seems like preferable behavior because it lets the caller know that the input string was odd.

[waddlesplash]

We haven't updated the Contributing guide just yet, but we have a Gerrit instance live at ​https://review.haiku-os.org -- so if you could submit your patch there, that would be best.

[waddlesplash]

Also, is this how upstream glibc solved the problem? If so, could you link to their fix commit?

[i80and]

This is not even close to how upstream glibc works. Unfortunately, they've diverged significantly from what exists in the haiku tree.

Would it be better to try and sync the implementation with upstream?

[i80and]

Made a new patch, using the following two diffs from upstream glibc:

• ​https://sourceware.org/git/?p=glibc.git;a=commit;h=405698e9
• ​https://sourceware.org/git/?p=glibc.git;a=commit;h=43b9d65

I'll try to figure out Gerrit

[waddlesplash]

Merged patch from Gerrit. Thanks!