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1 %//////////////////////////////////////////////////////////////////////////////
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2 %
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3 % Copyright (c) 2007-2017 Daniel Adler <dadler@uni-goettingen.de>,
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4 % Tassilo Philipp <tphilipp@potion-studios.com>
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5 %
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6 % Permission to use, copy, modify, and distribute this software for any
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7 % purpose with or without fee is hereby granted, provided that the above
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8 % copyright notice and this permission notice appear in all copies.
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9 %
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10 % THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
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11 % WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
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12 % MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
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13 % ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
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14 % WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
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15 % ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
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16 % OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
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17 %
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18 %//////////////////////////////////////////////////////////////////////////////
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19
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20 \newpage
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21 \section{\product{Dynload} C library API}
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22
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23 The \product{dynload} library encapsulates dynamic loading mechanisms and
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24 gives access to functions in foreign dynamic libraries and code modules.
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25
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26 \subsection{Loading code}
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27
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28 \begin{lstlisting}[language=c,label=dl-load]
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29 DLLib* dlLoadLibrary(const char* libpath);
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30 void dlFreeLibrary(void* libhandle);
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31 \end{lstlisting}
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32
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33 \lstinline{dlLoadLibrary} loads a dynamic library at \lstinline{libpath}
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34 and returns a handle to it for use in \lstinline{dlFreeLibrary} and
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35 \lstinline{dlFindSymbol} calls. Passing a null pointer for the \lstinline{libpath}
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36 argument is valid, and returns a handle to the main executable of the calling code.
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37 Also, searching libraries in library paths (e.g. by just passing the library's leaf
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38 name) should work, however, they are OS specific. Returns a null pointer on error.
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39
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40 \lstinline{dlFreeLibrary} frees the loaded library with handle \lstinline{pLib}.
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41
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42 \subsection{Retrieving functions}
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43
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44 \begin{lstlisting}[language=c]
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45 void* dlFindSymbol(void* libhandle, const char* symbol);
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46 \end{lstlisting}
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47
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48 This function returns a pointer to a symbol with name \lstinline{pSymbolName} in the
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49 library with handle \lstinline{pLib}, or returns a null pointer if the symbol cannot
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50 be found. The name is specified as it would appear in C source code (mangled if C++, etc.).
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51
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52 \subsection{Misc functions}
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53 \begin{lstlisting}[language=c]
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54 int dlGetLibraryPath(DLLib* pLib, char* sOut, int bufSize);
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55 \end{lstlisting}
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56
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57 This function can be used to get a copy of the path to the library loaded with handle
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58 \lstinline{pLib}. The parameter \lstinline{sOut} is a pointer to a buffer of size
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59 \lstinline{bufSize} (in bytes), to hold the output string. The return value is the size
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60 of the buffer (in bytes) needed to hold the null-terminated string, or 0 if it can't be
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61 looked up. If \lstinline{bufSize} \textgreater= return value \textgreater 1, a null-terminted string with the
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62 path to the library should be in \lstinline{sOut}. If it returns 0, the library name wasn't
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63 able to be found. Please note that this might happen in some rare cases, so make sure to always check.
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64
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65 \subsection{Symbol iteration}
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66
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67 \begin{lstlisting}[language=c]
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68 DLSyms* dlSymsInit(const char* libPath);
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69 void dlSymsCleanup(DLSyms* pSyms);
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70 int dlSymsCount(DLSyms* pSyms);
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71 const char* dlSymsName(DLSyms* pSyms, int index);
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72 const char* dlSymsNameFromValue(DLSyms* pSyms, void* value); /* symbol must be loaded */
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73 \end{lstlisting}
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74
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75
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76 These functions can be used to iterate over symbols. Since they can be used on libraries that are not linked, they are made
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77 for symbol name lookups, not to get a symbol's address. For that refer to
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78 \lstinline{dlFindSymbol}. \lstinline{dlSymsInit} will return a handle (or a null pointer
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79 on error) to the shared object specified by \lstinline{libPath}, to be used with the other dlSyms* functions. Note that contrary
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80 to loading and linking libraries, no (OS-specific) rules for searching libraries in library paths, etc. apply. The handle must be freed with
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81 \lstinline{dlSymsCleanup}. \lstinline{dlSymsCount} returns the number of
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82 symbols in the shared object, \lstinline{dlSymsName} and \lstinline{dlSymsNameFromValue}
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83 are used to lookup symbol names using an index or symbol's address, respectively,
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84 returning a null pointer on error. The names are returned as they would appear
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85 in C source code (mangled if C++, etc.). The address passed to \lstinline{dlSymsNameFromValue}
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86 must point to a loaded symbol.
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87
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