Why does fopen thown errno:22 when I use the file name with colon in Android?

Question

When I use the file name with colon like 2012-12-12 12:00:00, fopen will be failed and the error is Invalid argument.If I change the file name to 2012-12-12 12-00-00 it goes rightly.What does errno Invalid argument mean? I've tried to run command in Android by adb shell, I tried touch a file with colon in name, it was failed, but If I use vi to new a file with colon in name, it goes rightly.What is the matter with this?And I've check the path, no problem with it.

errno = 0;
FILE *fp = fopen("/sdcard/2012-12-12 12:00:00", "a");
if (fp == NULL) {
    strerror(errno)   // Invalid argument
    return;
}

fprintf(fp, "%s", "something");
fclose(fp);

You should print `strerror(errno)` in addition of `errno` (or use `perror`) — Basile Starynkevitch, Sep 08 '13 at 15:23
On my plain Ubuntu Linux system, errno 22 is `EINVAL`, as in "invalid argument". — unwind, Sep 08 '13 at 15:25
Yes, when I use `strerror(errno)`, it print `Invalid argument`, what does this mean? — Suge, Sep 08 '13 at 15:30

score 4 · Accepted Answer · answered Sep 08 '13 at 15:33

4

I suppose the problem arises because the colon : is used as a path-list separator under *NIX systems (e.g. to separate the pathnames listed in the PATH environment variable). Probably some internal processing went awry because of this.

answered Sep 08 '13 at 15:33

LorenzoDonati4Ukraine-OnStrike

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That was my first guess too, but then why does vi succeed in creating the file? – unwind Sep 08 '13 at 15:33
@unwind Well, I'm not sure if `:` is actually illegal at kernel level, so maybe it *can* be put in a filename, but how it is processed depends on the specific tool. – LorenzoDonati4Ukraine-OnStrike Sep 08 '13 at 15:36
2

The problem is not the path-list separator. The valid characters in file names depend on the file system, and according to the "possible duplicate" linked above, the colon is not allowed on a FAT32 file system. – Martin R Sep 08 '13 at 15:57
@MartinR Yep! Nice find! – LorenzoDonati4Ukraine-OnStrike Sep 08 '13 at 16:13
1

First Google hit for "android invalid file name colon" :-) – Martin R Sep 08 '13 at 16:17
@MartinR I googled it too, but probably didn't use the right keywords combinations. My google-fu is failing me, argh! :-) – LorenzoDonati4Ukraine-OnStrike Sep 08 '13 at 16:20

Why does fopen thown errno:22 when I use the file name with colon in Android?

1 Answers1