The ISO/IEC 9899-1999 C standard function fopen() is typically used to open an existing file or create a new one. However, fopen() does not provide a mechanism to determine indicate if an existing file has been opened or a new file has been created. This may lead to a program overwriting or accessing an unintended file.
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Compliant Solution 1
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The ISO/IEC 9899-1999 C standard{{fopen()}} function does not provide a mechanism to determine indicate if an existing file has been opened for writing or a new file has been created. However, the {{open()}} function as defined in the Open Group Base Specifications Issue 6 \[[Open Group 04|AA. C References#Open Group 04]\] is available on many platforms and provides such a mechanism. If the {{O_CREAT}} and {{O_EXCL}} flags are used together, the {{open()}} function fails when the file specified by {{file_name}} already exists. |
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