New GCC 7 Warnings

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Rumble
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3 years 8 months ago #8471 by Rumble

New GCC 7 Warnings was created by Rumble

With the upgrade of the server we now have GCC 8.2.1 (thanks Opie) and some new warnings (thanks Redhat). I'm surprised no one has posted about them yet. Below are a few examples.

shop.c: In function ‘shop_keeper’:
shop.c:802:48: warning: ‘%s’ directive output may be truncated writing up to 511 bytes into a region of size 503 [-Wformat-truncation=]
   snprintf(tempbuf, sizeof(tempbuf), "$n sells %s.", tempstr);
                                                ^~    ~~~~~~~
shop.c:802:3: note: ‘snprintf’ output between 11 and 522 bytes into a destination of size 512
   snprintf(tempbuf, sizeof(tempbuf), "$n sells %s.", tempstr);
   ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
shop.c:627:47: warning: ‘%s’ directive output may be truncated writing up to 511 bytes into a region of size 504 [-Wformat-truncation=]
   snprintf(tempbuf, sizeof(tempbuf), "$n buys %s.", tempstr);
                                               ^~    ~~~~~~~
shop.c:627:3: note: ‘snprintf’ output between 10 and 521 bytes into a destination of size 512
   snprintf(tempbuf, sizeof(tempbuf), "$n buys %s.", tempstr);
   ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
shop.c:627:47: warning: ‘%s’ directive output may be truncated writing up to 511 bytes into a region of size 504 [-Wformat-truncation=]
   snprintf(tempbuf, sizeof(tempbuf), "$n buys %s.", tempstr);
                                               ^~    ~~~~~~~
shop.c:627:3: note: ‘snprintf’ output between 10 and 521 bytes into a destination of size 512
   snprintf(tempbuf, sizeof(tempbuf), "$n buys %s.", tempstr);
   ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
shop.c:627:47: warning: ‘%s’ directive output may be truncated writing up to 511 bytes into a region of size 504 [-Wformat-truncation=]
   snprintf(tempbuf, sizeof(tempbuf), "$n buys %s.", tempstr);
                                               ^~    ~~~~~~~

These are warnings, not bugs and is expected behavior. The only result is snprintf truncating the text. Redhat explains their valid reasoning here.

The solution would be to define a larger temp buf size as required. But I'm not sure it is worth it.

Warnings can be hidden with Makefile change
MYFLAGS = -Wall
to
MYFLAGS = -Wall -Wno-format-truncation

Appreciate everyone's thoughts or if someone has already tackled this.

Rumble
The Builder Academy
tbamud.com 9091
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thomas
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3 years 8 months ago #8472 by thomas

Replied by thomas on topic New GCC 7 Warnings

I think the correct fix for those is to make the tempstr 15 chars shorter.

I'll try running a build and see how much trouble they are.

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thomas
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3 years 8 months ago #8473 by thomas

Replied by thomas on topic New GCC 7 Warnings

Some of them were quite bad. I've made a PR with fixes. github.com/tbamud/tbamud/pull/74

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Rumble
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3 years 8 months ago #8474 by Rumble

Replied by Rumble on topic New GCC 7 Warnings

Thanks Thomas, I plan to put together the 2020 release next week. Appreciate the help. Thanks for Merging Wyld.

Rumble
The Builder Academy
tbamud.com 9091
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