RE: [PATCH v2 1/4] tools/nolibc: sys.h: add __syscall() and __sysret() helpers

From: Zhangjin Wu

Sent: 06 June 2023 09:10

most of the library routines share the same code model, let's add two helpers to simplify the coding and shrink the code lines too.

...

+/* Syscall return helper, set errno as -ret when ret < 0 */ +static inline __attribute__((always_inline)) long __sysret(long ret) +{

• if (ret < 0) {

• SET_ERRNO(-ret);
  

• ret = -1;
  

• }
• return ret;

+}

If that right? I thought that that only the first few (1024?) negative values got used as errno values.

Do all Linux architectures even use negatives for error? I thought at least some used the carry flag. (It is the historic method of indicating a system call failure.)

David

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