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POread() only reads a few bytes from file
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  1. POread() only reads a few bytes from file
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    copied!<p>I wanted to read the content of a file using the read() function. I tried the following:</p> <pre><code>#define BUFFER_LENGTH (1024) char buffer[BUFFER_LENGTH]; // The first version of the question had a typo: // void read_file(const char filename) // This would produce a compiler warning. void read_file(const char *filename) { ssize_t read_bytes = 0; // The first version had the mode in hex instead of octal. // // int fd_in = open(filename, O_RDONLY, 0x00644); // // This does not cause problems here but it is wrong. // The mode is now octal (even if it is not needed). int fd_in = open(filename, O_RDONLY, 0644); if (fd_in == -1) { return; } do { read_bytes = read(fd_in, buffer, (size_t) BUFFER_LENGTH); printf("Read %d bytes\n", read_bytes); // End of file or error. if (read_bytes &lt;= 0) { break; } } while (1); close(fd_in); } </code></pre> <p>I am using 'gcc (GCC) 3.4.2 (mingw-special)' on a Windows 7 system.</p> <p>The strange behaviour I get is that not all the content is read. For example, I have a file</p> <pre><code>05.01.2012 12:28 15.838 hello.exe </code></pre> <p>and when I try to read it I get:</p> <pre><code>Read 216 bytes Read 0 bytes </code></pre> <p>As far as I know read() should keep reading until it reaches the end of the file. While does it report an end of file (0) the second time it is called?</p> <p>Maybe I am missing something obvious but I cannot see it. I have read <a href="http://www.gnu.org/software/libc/manual/html_node/Opening-and-Closing-Files.html#Opening-and-Closing-Files" rel="nofollow">this document</a> and <a href="http://www.gnu.org/software/libc/manual/html_node/I_002fO-Primitives.html#I_002fO-Primitives" rel="nofollow">this document</a> over and over again and I cannot find what I am doing wrong. Does anyone have any clue?</p> <p><strong>EDIT</strong></p> <p>Thanks for the hint! It is a typo in the question (I have corrected it). It is correct in the source code.</p>
 

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