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avrdudes / avr-libc

The AVR-LibC package provides a subset of the standard C library for AVR 8-bit RISC microcontrollers.
https://avrdudes.github.io/avr-libc/
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[bug #11494] strtol() return wrong value in the underflow case #96

Closed avrs-admin closed 2 years ago

avrs-admin commented 2 years ago

Wed 05 Jan 2005 08:31:21 AM CET

This is very old bug. strtol() must return LONG_MIN for inputs too small. Original Berkeley version do it.  But avr-libc's version, for example, "-5000000000" --> -705032704 (simulavr, avr-gcc 3.3.4). You can reproduce such result on any 32-bit computer.

The reason is the attemption to negative LONG_MIN value (0x80000000). Attached patch correct this mistake. (And it excude compiler warnings in comparison).

file #2324: strtol-20050105.diff

This issue was migrated from https://savannah.nongnu.org/bugs/?11494

avrs-admin commented 2 years ago

Thu 06 Jan 2005 08:29:29 AM CET

Look, please, the optimized strtol, patch #3618. Twice speed up, and 32 bytes stack usage decrease. Code size the same.

avrs-admin commented 2 years ago

Eric Weddington Mon 10 Jan 2005 11:51:37 PM CET

In the patch for this bug, can you rewrite your typecasts using the types found in stdint.h? (for example uint32_t, uint16_t)

That way it can start to be -mint8 compatible.

Thanks! Eric

avrs-admin commented 2 years ago

Tue 11 Jan 2005 11:16:21 PM CET

My opinion about "-mint8 compatibility":

Without -mint8 option, original (and patched) strtol' returnlong' value, that is clipped in bounds LONG_MIN and LONG_MAX.  Such, strtol("5000000000",0,0) must return 2147483647. With -mint8 option, strtol' must also returnlong' value, clipped by LONG_MIN and LONG_MAX also.  But, due to reduced size of `long' (and reduced LONG_MAX, LONG_MIN), the result of strtol("5000000000",0,0) must be 32767. Such behavior agree, for example, glibc.  On computer with 64-bit long, result of strtol("5000000000",0,0) will be 5000000000.

In such sence, strtol (original and patched) work true with any size of `long'.

But if anybody is needing a function, that must return value, "at least as 32 bits", it is necessity to write another function, with another name, like: int32_t strto32 (const char **, char***, int) .

Thanks.

P.S.  In patch #3618 (strtol optimization) second part of source contain test for strtol with strings, like: { "2147483647", 0, 0x7fffffff, 0, 10 } This test do not work with `-mint8' option and must be rewrited with conditional compilation usage.

avrs-admin commented 2 years ago

Wed 12 Jan 2005 04:03:30 AM CET

Sorry, a mistake in last comment. Read as: But if anybody is needing a function, that must return value, "exactly 32 bits length"...

avrs-admin commented 2 years ago

Joerg Wunsch Tue 25 Jan 2005 11:57:09 AM CET

Your patch package has been incorporated, bolshoye spasibo!